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+% \iffalse THIS IS A META-COMMENT
+%<*dtx>
+\ProvidesFile
+%========================================================================
+ {NATBIB.DTX}
+%========================================================================
+%</dtx>
+%% Copyright 1993-1999 Patrick W Daly
+%% Max-Planck-Institut f\"ur Aeronomie
+%% Max-Planck-Str. 2
+%% D-37191 Katlenburg-Lindau
+%% Germany
+%% E-mail: daly@linmpi.mpg.de
+%
+% This program can be redistributed and/or modified under the terms
+% of the LaTeX Project Public License Distributed from CTAN
+% archives in directory macros/latex/base/lppl.txt; either
+% version 1 of the License, or any later version.
+%
+% This is a contributed file to the LaTeX2e system.
+% -------------------------------------------------
+% This is a LaTeX package to modify \cite and \thebibliography for author-year
+% systems of bibliographic citation; will also work with
+% numerical systems, allowing simplified style changes for them too.
+% Installation:
+% LaTeX this file: creates docstrip installation file natbib.ins
+% AND the (LaTeX2e) documentation
+% (La)TeX natbib.ins: creates package file natbib.sty
+% and optionally documentation driver natbib.drv
+% (natbib.ins may be edited as needed)
+% Docstrip options available:
+% package - to produce a (LaTeX2e) package .sty file
+% notes - to produce a reference sheet for natbib usage
+% driver - to produce a driver file to print the documentation
+% 209 - (with package) for style file that runs under LaTeX 2.09
+% subpack - (with package) for coding included in other packages
+% all - (with package) to include all author-year systems
+% else individually with:
+% apalike, newapa, chicago, harvard, authordate, astron
+% agu - (with package,subpack) for inclusion in aguplus package
+% egs- (with package,subpack) for inclusion in egs package
+% nopreonly - allows \citestyle and \bibpunct to be used anywhere
+%--------------------------------------------------------------------------
+%<*!subpack>
+%<package&209>\def\ProvidesPackage#1#2]
+%<package&209> {\typeout{Style option `#1'#2]}}
+%
+% *** Identify the package file:-
+%<package&!209>\NeedsTeXFormat{LaTeX2e}[1995/06/01]
+% (Need LaTeX2e release 3 for option definition with single #)
+%<package>\ProvidesPackage{natbib}
+%</!subpack>
+%
+% *** Provide command to dislay module version
+%<package&subpack>\def\ModuleVersion#1[#2]{}
+%<package&subpack> \ModuleVersion{natbib}
+%
+% *** Provide command to identify reference sheet (notes)
+%<notes>\NeedsTeXFormat{LaTeX2e}
+%<notes>\def\DescribesFile#1 [#2 #3 #4]
+%<notes> {\def\filename{#1}\def\filedate{#2}\def\fileversion{#3}}
+%<notes>\DescribesFile{natbib}
+%
+% *** Identify the driver file:-
+%<driver>\NeedsTeXFormat{LaTeX2e}
+%<driver>\ProvidesFile{natbib.drv}
+%
+% *** The DATE, VERSION, and other INFO
+%\fi
+%\ProvidesFile{natbib}
+ [1999/05/28 7.0 (PWD)]
+% \changes{4.0}{1993 Aug 19}{First documented release}
+% \changes{4.1}{1993 Oct 4}{Simplification of \cs{@citeapalk}}
+% \changes{4.1a}{1993 Oct 14}{Add \texttt{rev} option for reversed comments
+% in \cs{cite}}
+% \changes{4.1b}{1993 Oct 18}{Add \cs{bibfont} to list definition =\cs{relax}}
+% \changes{4.2}{1993 Oct 22}{Add coding for AGU, NLINPROC}
+% \changes{4.2}{1993 Nov 20}{Add more coding for AGU}
+% \changes{4.3a}{1994 Feb 24}{First additions for \LaTeXe}
+% \changes{5.0}{1994 May 18}{Revised for \LaTeXe{} and 2.09}
+% \changes{5.0}{1994 May 18}{Remove obsolete JGR, GRL coding}
+% \changes{5.0}{1994 May 18}{Add \cs{citeauthor}, \cs{citeyear}}
+% \changes{5.0}{1994 May 18}{Two optional texts for \cs{cite} so \texttt{rev}
+% option obsolete}
+% \changes{5.0}{1994 May 18}{\LaTeXe\ options to select punctuation}
+% \changes{5.1}{1994 Jun 22}{Conform to first official release of \LaTeXe}
+% \changes{5.1}{1994 Jun 22}{Separate \LaTeX\ and 2.09 files}
+% \changes{5.1}{1994 Jun 22}{Put doc driver first}
+% \changes{5.2}{1994 Aug 25}{Fix up 2.09 style to run in compatibility mode}
+% \changes{5.2}{1994 Aug 25}{\cs{citeauthor}, \cs{citeyear} make BibTeX
+% entry in aux file}
+% \changes{5.2}{1994 Aug 25}{\cs{@citex} defined as in \LaTeXe}
+% \changes{5.2}{1994 Aug 25}{Local config file \texttt{natbib.cfg} read in}
+% \changes{5.3}{1994 Sep 13}{Add \cs{citefullauthor}, options \texttt{angle},
+% \texttt{curly}}
+% \changes{5.3}{1994 Sep 19}{Add star version of \cs{cite} for full authors}
+% \changes{5.3}{1994 Sep 26}{Fix accents in citations with proper definition
+% of \cs{protect}}
+% \changes{5.4}{1994 Nov 24}{Add space in \cs{@citex} for text cites}
+% \changes{5.4}{1994 Nov 24}{Replace \cs{if@tempswa} by \cs{ifNAT@swa}}
+% \changes{5.4}{1994 Nov 24}{Add superscript citation type to \cs{bibpunct}}
+% \changes{5.4}{1994 Nov 24}{Add \cs{@citesuper}, fix up bugs in superscripts}
+% \changes{5.4}{1994 Nov 24}{Define \cs{@citexnum} as in \LaTeXe}
+% \changes{5.4}{1995 Feb 03}{Add \cs{citestyle} same as \cs{bibstyle}}
+% \changes{5.4}{1995 Feb 08}{For repeated years and authors, print just letter}
+% \changes{5.5}{1995 Mar 13}{Add \cs{bibhang} and command space in
+% \cs{@cite}}
+% \changes{5.5}{1995 Mar 16}{Add \cs{citealt} for citation with no
+% parentheses}
+% \changes{5.5}{1995 Mar 24}{Reorganize internal commands, using \cs{NAT@}
+% prefixes}
+% \changes{5.5}{1995 Mar 24}{Punctuation selection commands \cs{bibpunct},
+% \cs{citestyle} are now preamble only, whereas previously they had to
+% come after the preamble}
+% \changes{5.5}{1995 May 14}{Change names of punctuation commands to
+% \cs{NAT@...}}
+% \changes{6.0}{1995 Sep 4}{Allow numerical styles with author-year
+% \texttt{bst} files}
+% \changes{6.0}{1995 Sep 21}{Add automatic indexing of citations}
+% \changes{6.0}{1995 Sep 29}{Accommodate \texttt{index} package}
+% \changes{6.1}{1995 Nov 22}{Fixed for \LaTeXe\ \texttt{1995/12/01}}
+% \changes{6.1}{1995 Dec 4}{Make more robust against changes to internals}
+% \changes{6.1a}{1995 Dec 19}{Fix test for changed citations}
+% \changes{6.2}{1996 Jan 10}{Replace all \cs{uppercase}}
+% \changes{6.2}{1996 Jan 11}{Add \cs{citet}}
+% \changes{6.2}{1996 Feb 2}{Fix superscript size}
+% \changes{6.2}{1996 Mar 05}{Add length \cs{bibsep} for linespacing between
+% references}
+% \changes{6.2}{1996 Apr 15}{Fix clash with \texttt{amsart} and
+% \texttt{amsbook}}
+% \changes{6.3}{1996 Jun 10}{Allow \texttt{showkeys} to be loaded first}
+% \changes{6.3}{1996 Jun 17}{Fix punctuation for \texttt{plainnat}}
+% \changes{6.3}{1996 Jun 17}{Suppress extra labels with numericals}
+% \changes{6.4}{1996 Jun 18}{Provide \cs{bibname} and \cs{refname}}
+% \changes{6.4}{1996 Jun 27}{Change \texttt{nlinproc} option to \texttt{egs}}
+% \changes{6.4}{1996 Sep 1}{Make compatible with \texttt{chapterbib.sty}}
+% \changes{6.4}{1996 Sep 12}{Fix spacing for superscripts}
+% \changes{6.4}{1996 Sep 12}{Extra letter printed with \cs{citeyear}}
+% \changes{6.4}{1996 Sep 13}{Add compression and sorting of numerical citations}
+% \changes{6.4}{1996 Oct 2}{Make compatible with \texttt{hyperref.sty}}
+% \changes{6.5}{1996 Dec 11}{KOMA script compatibility}
+% \changes{6.5}{1997 Jan 10}{For EGS, no blank line between references}
+% \changes{6.5}{1997 Jan 30}{Recode notes so they work with \cs{citet} and
+% \cs{citep}; change documentation to stress these commands over \cs{cite}}
+% \changes{6.5}{1997 Feb 5}{Fix KOMA script properly}
+% \changes{6.6}{1997 Apr 6}{Fix \cs{nocite} to work with \texttt{chapterbib}}
+% \changes{6.6}{1997 May 26}{Let \cs{citealt} have full \cs{cite} syntax}
+% \changes{6.6}{1997 Jun 4}{Add \cs{citeyearpar}}
+% \changes{6.6}{1997 Jun 4}{Add sorting of author--year citations}
+% \changes{6.6}{1997 Jun 12}{Add \cs{citealp} like \cs{citep} without parentheses}
+% \changes{6.6}{1997 Jun 24}{Fix \texttt{showkeys} functionality}
+% \changes{6.6}{1997 Jun 25}{Improve \texttt{hyperref} functionality}
+% \changes{6.6}{1997 Jun 30}{Fix bug in \cs{NAT@citex}}
+% \changes{6.7}{1997 Jul 14}{Add \texttt{longnamesfirst} option}
+% \changes{6.7}{1997 Sep 12}{Fix interface with \texttt{showkeys}}
+% \changes{6.7}{1997 Nov 10}{Fix interface with \texttt{babel}}
+% \changes{6.7}{1997 Nov 11}{Add reference sheet extraction}
+% \changes{6.8}{1997 Dec 1}{Permit \cs{@biblabel} to be user modified}
+% \changes{6.8}{1998 Feb 19}{Fix hyperref bug in \cs{citep}}
+% \changes{6.8a}{1998 Mar 6}{Correct wrong name for \texttt{longnamesfirst}
+% in the documentation}
+% \changes{6.8a}{1998 May 14}{\cs{@biblabel} only redefinable for numerical
+% mode}
+% \changes{6.8b}{1998 July 6}{Hyperref: to work with \texttt{chapterbib} and
+% breaks links in textual citations}
+% \changes{6.8c}{1998 July 14}{Hyperref: remove opening brace and notes from
+% link}
+% \changes{6.8d}{1998 Nov 23}{Fix bug in \texttt{super} option; suppress brackets}
+% \changes{6.9}{1999 Jan 22}{Fix bug with \cs{makeindex}}
+% \changes{6.9}{1999 Feb 23}{Update copyright notice}
+% \changes{6.9}{1999 Mar 26}{Babel test made more general}
+% \changes{7.0}{1999 May 7}{With empty year, act like \cs{citeauthor}}
+% \changes{7.0}{1999 May 21}{Correct \cs{bibsection} for \texttt{amsbook}}
+%
+% \CheckSum{2346}
+% \CharacterTable
+% {Upper-case \A\B\C\D\E\F\G\H\I\J\K\L\M\N\O\P\Q\R\S\T\U\V\W\X\Y\Z
+% Lower-case \a\b\c\d\e\f\g\h\i\j\k\l\m\n\o\p\q\r\s\t\u\v\w\x\y\z
+% Digits \0\1\2\3\4\5\6\7\8\9
+% Exclamation \! Double quote \" Hash (number) \#
+% Dollar \$ Percent \% Ampersand \&
+% Acute accent \' Left paren \( Right paren \)
+% Asterisk \* Plus \+ Comma \,
+% Minus \- Point \. Solidus \/
+% Colon \: Semicolon \; Less than \<
+% Equals \= Greater than \> Question mark \?
+% Commercial at \@ Left bracket \[ Backslash \\
+% Right bracket \] Circumflex \^ Underscore \_
+% Grave accent \` Left brace \{ Vertical bar \|
+% Right brace \} Tilde \~}
+%
+% \iffalse
+%<*install>
+%^^A =============================================
+%^^A Here is the docstrip installation file
+%^^A It is written on first LaTeX run if it
+%^^A does not already exist
+%^^A =============================================
+\begin{filecontents*}{natbib.ins}
+% File: natbib.ins
+% Copyright 1999 Patrick W. Daly
+%
+% This file can be redistributed and/or modified under the terms
+% of the LaTeX Project Public License Distributed from CTAN
+% archives in directory macros/latex/base/lppl.txt; either
+% version 1 of the License, or any later version.
+%
+% It is an installation file for extracting package and driver
+% files from the original source file. Simply process it under
+% TeX or LaTeX. It works with Docstrip versions before and after
+% December 1995.
+
+\def\batchfile{natbib.ins}
+\input docstrip
+
+\preamble
+=============================================
+IMPORTANT NOTICE:
+
+This program can be redistributed and/or modified under the terms
+of the LaTeX Project Public License Distributed from CTAN
+archives in directory macros/latex/base/lppl.txt; either
+version 1 of the License, or any later version.
+
+This is a generated file.
+It may not be distributed without the original source file \inFileName.
+
+Full documentation can be obtained by LaTeXing that original file.
+Only a few abbreviated comments remain here to describe the usage.
+=============================================
+\endpreamble
+\postamble
+
+<<<<< End of generated file <<<<<<
+\endpostamble
+\keepsilent
+
+% Docstrip before Dec 95 does not have \generate syntax, nor
+% \declarepreamble. Must redefine them. The \generateFile called
+% for each output file individually.
+% Docstrip before Dec 96 cannot interprete multiline \if..\fi
+% Thus for maximum compatibility, have only one-line conditionals
+
+\let\oldDS F\relax
+\expandafter\ifx\csname generate\endcsname\relax \let\oldDS T\relax\fi
+\if\oldDS T \def\declarepreamble#1{\preamble}\fi
+\if\oldDS T \def\declarepostamble#1{\postamble}\fi
+\if\oldDS T \generateFile{natbib.sty}{f}{\from{natbib.dtx}{package,all}} \fi
+
+\declarepreamble\refsheet
+=============================================
+IMPORTANT NOTICE:
+
+This program can be redistributed and/or modified under the terms
+of the LaTeX Project Public License Distributed from CTAN
+archives in directory macros/latex/base/lppl.txt; either
+version 1 of the License, or any later version.
+
+This is a generated file.
+It may not be distributed without the original source file \inFileName.
+
+This is a Reference Sheet for natbib. It consists of excerpts from the
+original source file.
+
+For more details, LaTeX the source \inFileName.
+==============================================
+\endpreamble
+
+\declarepostamble\refsheetq
+
+End of Reference Sheet file
+
+\endpostamble
+
+\ifx\oldDS T \generateFile{natnotes}{f}{\from{natbib.dtx}{notes}}\fi
+
+\declarepreamble\driver
+============================================
+This is the driver file to produce the LaTeX documentation
+from the original source file \inFileName.
+
+Make changes to it as needed. (Never change the file \inFileName!)
+============================================
+\endpreamble
+
+\declarepostamble\driverq
+
+End of documentation driver file.
+\endpostamble
+
+\ifx\oldDS T \generateFile{natbib.drv}{f}{\from{natbib.dtx}{driver}}\fi
+
+\ifx\oldDS T \let\askforoverwritefalse\relax\def\generate#1{}\fi
+
+\askforoverwritefalse
+\generate{\file{natbib.sty}{\from{natbib.dtx}{package,all}}
+ \file{natnotes}{\usepreamble\refsheet\usepostamble\refsheetq
+ \from{natbib.dtx}{notes}}
+ \file{natbib.drv}{\usepreamble\driver\usepostamble\driverq
+ \from{natbib.dtx}{driver}}
+ }
+
+\obeyspaces
+\Msg{*********************************************}%
+\Msg{* For documentation, process natbib.dtx *}%
+\Msg{* or the driver file natbib.drv *}%
+\Msg{* For reference sheet, process natnotes.tex *}
+\Msg{*********************************************}
+\end{filecontents*}
+%</install>
+%<*driver>
+\documentclass{ltxdoc}
+%<driver>%\documentclass[twoside]{ltxdoc}
+%<driver>%\documentclass[a4paper]{ltxdoc}
+%<driver>%\documentclass[twoside,a4paper]{ltxdoc}
+\raggedbottom
+
+ %** To include the detailed explanation of the coding, comment out
+ %** the next line
+\OnlyDescription
+
+ %** To produce a command index: add the following line for one run,
+ %** then run makeindex -s gind.ist natbib
+ %** and reprocess, with or without this line (much faster without)
+%<driver>% \EnableCrossrefs\CodelineIndex
+
+ %** To produce a change history: add the following line for one run,
+ %** then run makeindex -s gglo.ist -o natbib.gls natbib.glo
+ %** and reprocess, with or without this line (faster without)
+%<driver>% \RecordChanges
+
+\DisableCrossrefs %May stay; zapped by \EnableCrossrefs
+\CodelineNumbered %May stay
+
+\begin{document}
+ \DocInput{natbib.dtx}
+\end{document}
+%</driver>
+%<*notes>
+%^^A ***************************
+%^^A Preamble to the Reference Sheet
+%^^A ***************************
+\documentclass{article}
+
+\setlength{\parindent}{0pt}
+\setlength{\parskip}{1ex}
+\setlength{\textwidth}{\paperwidth}
+\addtolength{\textwidth}{-2in}
+\setlength{\oddsidemargin}{0pt}
+\setlength{\textheight}{\paperheight}
+
+\addtolength{\textheight}{-\headheight}
+\addtolength{\textheight}{-\headsep}
+\addtolength{\textheight}{-\footskip}
+\addtolength{\textheight}{-2in}
+\makeatletter
+\def\@listI{\leftmargin\leftmargini
+ \topsep\z@ \parsep\parskip \itemsep\z@}
+\let\@listi\@listI
+\@listi
+\makeatother
+\newcommand{\head}[1]{\subsubsection*{#1}}
+
+\pagestyle{headings}
+\markright{Reference sheet: \texttt{natbib}}
+
+\usepackage{shortvrb}
+\MakeShortVerb{\|}
+
+\begin{document}
+\thispagestyle{plain}
+
+%</notes>
+%\fi
+%
+% \DoNotIndex{\begin,\CodelineIndex,\CodelineNumbered,\def,\DisableCrossrefs}
+% \DoNotIndex{\DocInput,\documentclass,\EnableCrossrefs,\end,\GetFileInfo}
+% \DoNotIndex{\NeedsTeXFormat,\OnlyDescription,\RecordChanges,\usepackage}
+% \DoNotIndex{\ProvidesClass,\ProvidesPackage,\ProvidesFile,\RequirePackage}
+% \DoNotIndex{\LoadClass,\PassOptionsToClass,\PassOptionsToPackage}
+% \DoNotIndex{\DeclareOption,\CurrentOption,\ProcessOptions,\ExecuteOptions}
+% \DoNotIndex{\AtEndOfClass,\AtEndOfPackage,\AtBeginDocument,\AtEndDocument}
+% \DoNotIndex{\InputIfFileExists,\IfFileExists,\ClassError,\PackageError}
+% \DoNotIndex{\ClassWarning,\PackageWarning,\ClassWarningNoLine}
+% \DoNotIndex{\PackageWarningNoLine,\ClassInfo,\PackageInfo,\MessageBreak}
+% \DoNotIndex{\space,\protect,\DeclareRobustCommand,\CheckCommand}
+% \DoNotIndex{\newcommand,\renewcommand,\providecommand,\newenvironment}
+% \DoNotIndex{\renewenvironment,\newif,\newlength,\newcounter,\setlength}
+% \DoNotIndex{\setcounter,\if,\ifx,\ifcase,\ifnum,\ifdim,\else,\fi}
+% \DoNotIndex{\texttt,\textbf,\textrm,\textsl,\textsc,\reset@font}
+% \DoNotIndex{\textup,\textit,\textmd,\textsf,\emph,\futurelet}
+% \DoNotIndex{\ttfamily,\rmfamily,\sffamily,\mdseries,\bfseries,\upshape}
+% \DoNotIndex{\slshape,\scshape,\itshape,\em,\LaTeX,\LaTeXe}
+% \DoNotIndex{\filename,\fileversion,\filedate,\let,\makeindex}
+% \DoNotIndex{\@auxout,\@for,\@gobble,\@ifnextchar,\@m,\@mkboth,\@nil}
+% \DoNotIndex{\@noitemerr,\@tempa,\@tempswafalse,\@tempswatrue,\@warning}
+% \DoNotIndex{\advance,\arabic,\AtBeginDocument,\bf,\bibname,\chapter}
+% \DoNotIndex{\citation,\clubpenalty,\CodelineNumbered,\csname}
+% \DoNotIndex{\DisableCrossrefs,\do,\edef,\else,\endcsname,\endlist}
+% \DoNotIndex{\expandafter,\fi,\gdef,\global,\hbox,\hfill,\hskip,\hspace}
+% \DoNotIndex{\if,\if@filesw,\if@tempswa,\ifx,\immediate,\itemindent,\labelsep}
+% \DoNotIndex{\labelwidth,\lastskip,\leftmargin,\list,\mbox,\newblock}
+% \DoNotIndex{\newpage,\p@enumiv,\parindent,\penalty,\refname}
+% \DoNotIndex{\relax,\section,\settowidth,\sfcode,\sloppy,\small,\string}
+% \DoNotIndex{\theenumiv,\thepage,\unskip,\uppercase,\usecounter,\vskip}
+% \DoNotIndex{\widowpenalty,\write,\xdef,\z@,\catcode,\ifnum,\the}
+% \DoNotIndex{\.,\@empty,\@ifundefined,\@latex@warning,\@minus,\@plus,\ }
+% \DoNotIndex{\document,\@namedef,\@listi,\markboth,\or,\p@}
+% \DoNotIndex{\listparindent,\noexpand,\par,\parsep,\pb,\pbf,\pbfseries}
+% \DoNotIndex{\pc,\pd,\pem,\pit,\pitshape,\pmdseries,\prm,\prmfamily,\psc}
+% \DoNotIndex{\pscshape,\psf,\psffamily,\psl,\pslshape,\ptt,\pttfamily}
+% \DoNotIndex{\pupshape,\@iden,\@firstofone,\@unexpandable@protect}
+% \DoNotIndex{\&,\{,\},\bibitem,\bibindent,\if@draft,\typeout}
+% \DoNotIndex{\@ifclassloaded,\@ifstar,\@onlypreamble,\@preamblecmds}
+% \DoNotIndex{\addtolength,\endinput,\@bsphack,\begingroup,\@wrindex}
+% \DoNotIndex{\@listctr,\bibname,\enddocument,\hfil,\ignorespaces,\item}
+% \DoNotIndex{\NAT@temp,\refname,\stepcounter,\@ifpackageloaded}
+% \DoNotIndex{\@gobbletwo,\index,\itemsep,\markright,\scriptsize}
+% \DoNotIndex{\textsuperscript,\@undefined}
+% \DoNotIndex{\@celt,\@cite@list,\@citea,\@citeb,\@compress@cite}
+% \DoNotIndex{\@bsphack,\@esphack,\@h@ld,\@make@cite@list,\@ne}
+% \DoNotIndex{\@sort@celt,\@tempcnta,\@tempcntb,\delimiter,\endgroup}
+% \DoNotIndex{\ifcat,\m@ne,\number}
+% \DoNotIndex{\@markboth,\@mkboth,\nobreak,\SK@,\SK@@citex}
+% \DoNotIndex{\SK@@label,\SK@@ref,SK@def,\SK@lbibitem,\bbl@redefine}
+% \DoNotIndex{\@safe@activesfalse,\@save@activestrue,\active@prefix}
+%
+% \setcounter{IndexColumns}{2}
+% \setlength{\IndexMin}{10cm}
+% \setcounter{StandardModuleDepth}{1}
+%
+% \hyphenation{par-en-the-ti-cal}
+%
+% \GetFileInfo{natbib}
+%
+% \title{{\bfseries Natural Sciences Citations and References}\\
+% (Author--Year and Numerical Schemes)}
+%
+% \author{Patrick W. Daly}
+%
+% \date{This paper describes package \texttt{\filename}\\
+% version \fileversion{} from \filedate.
+% }
+%
+% \maketitle
+%
+% \pagestyle{myheadings}
+% \markboth{P. W. Daly}{NATURAL SCIENCES CITATIONS AND REFERENCES}
+%
+% \iffalse % The following lines belong to both the documentation and notes
+%<*notes>
+% \fi
+\newcommand{\btx}{\textsc{Bib}\TeX}
+\newcommand{\thestyle}{\texttt{\filename}}
+% \iffalse % These lines belong only to the notes
+\begin{center}{\bfseries\Large
+ Reference sheet for \thestyle\ usage}\\
+ \large(Describing version \fileversion\ from \filedate)
+\end{center}
+
+\begin{quote}\slshape
+For a more detailed description of the \thestyle\ package, \LaTeX\ the
+source file \thestyle\texttt{.dtx}.
+\end{quote}
+%</notes>
+% \fi
+%
+%^^A In order to keep all marginal notes on the one (left) side:
+%^^A (otherwise they switch sides disasterously with twoside option)
+% \makeatletter \@mparswitchfalse \makeatother
+%
+% \begin{abstract}
+% \iffalse % First line is Reference Sheet only, rest for both doc and Ref. Sheet
+%<*notes>
+\head{Overview}
+% \fi
+The \thestyle\ package is a reimplementation of the \LaTeX\ |\cite| command,
+to work with both author--year and numerical citations. It is compatible with
+the standard bibliographic style files, such as \texttt{plain.bst}, as well as
+with those for \texttt{harvard}, \texttt{apalike}, \texttt{chicago},
+\texttt{astron}, \texttt{authordate}, and of course \thestyle.
+
+% \iffalse
+%</notes>
+% \fi
+% In contrast to the packages listed above, the \thestyle{} package supports not
+% only the various author--year bibliography styles, but also those for standard
+% numerical citations. In fact, it can also produce numerical citations even
+% with an author--year bibliographic style, something that permits easy
+% switching between the two citation modes. To this end, replacements for the
+% standard \LaTeX\ \texttt{.bst} files are also provided.
+%
+% It is possible to define the citation \emph{style} (type of brackets and
+% punctuation between citations) and even to associate it with the name of
+% the bibliographic style so that it is automatically activated. Citation
+% styles can be defined for local \texttt{.bst} files by means of a
+% configuration file \thestyle\texttt{.cfg}.
+%
+% It is compatible with the packages: \texttt{babel}, \texttt{index},
+% \texttt{showkeys}, \texttt{chapterbib}, \texttt{hyperref}, \texttt{koma} and
+% with the classes \texttt{amsbook} and \texttt{amsart}. It can also emulate the
+% sorting and compressing functions of the \texttt{cite} package (with which it
+% is otherwise incompatible).
+%
+% The \thestyle\ package therefore acts as a single, flexible interface for
+% most of the available bibliographic styles.
+%
+% \end{abstract}
+%
+% \newpage\tableofcontents\newpage
+%
+% \section{Introduction}
+% The first problem of using author--year literature citations with standard
+% \LaTeX{} is that the two forms of citations are not supported. These are:
+% \begin{quote}
+% textual: \dots\ as shown by Jones et al. (1990) \dots\\
+% parenthetical: It has been shown (Jones et al., 1990) that \dots
+% \end{quote}
+% There is only one |\cite| command to do both jobs.
+%
+% A second problem is that the \texttt{thebibliography} environment for
+% listing the references insists on including the {\em labels\/} in the
+% list. These labels are normally the numbers, needed for referencing. In
+% the author--year system, they are superfluous and should be left off.
+% Thus, if one were to make up a bibliography with the author--year as
+% label, as
+% \begin{quote}
+% \begin{verbatim}
+% \begin{thebibliography}{...}
+% \bibitem[Jones et al., 1990]{jon90}
+% Jones, P. K., . . .
+% \end{thebibliography}
+% \end{verbatim}
+% \end{quote}
+% then |\cite{jon90}| produces the parenthetical citation [Jones et al.,
+% 1990], but there is no way to get the textual citation. Furthermore,
+% the citation text will also be included in the list of references.
+%
+% The final problem is to find a \btx{} bibliography style that will be
+% suitable.
+%
+% \section{Previous Solutions}
+% \begin{quote}\slshape
+% This section may not be of interest to all users. To find out how to use
+% \thestyle\ without reading about the historical background, go to
+% Section~\ref{sec:usage}.
+% \end{quote}
+%
+% Although the author--year citation mode is not supported by
+% \emph{standard} \LaTeX, there are a number of contributed packages that
+% try to solve this problem. The various bibliographic styles
+% (\texttt{.bst} files) that exist are usually tailored to be used with a
+% particular \LaTeX{} package.
+%
+% I have found a large number of \texttt{.bst} files on file servers that may
+% act as indicators of the various systems available.
+%
+% \subsection{The \texttt{natsci.bst} Style}
+% What gave me my first inspiration was Stephen Gildea's \texttt{natsci.bst}
+% for use with his \texttt{agujgr.sty} file. This showed me that the problem
+% was solvable. However, Gildea's style formats |\bibitem| just as I
+% illustrated above: with an optional label consisting of abbreviated
+% authors and year. Thus only parenthetical citations can be accommodated.
+% The list of references, however, is fixed up in his style files.
+%
+% \subsection{The \texttt{apalike.bst} Style}
+% Oren Patashnik, the originator of \btx{} and the standard \texttt{.bst}
+% files, has also worked on an author--year style, called \texttt{apalike.bst}
+% with a corresponding \texttt{apalike.sty} to support it. Again, only the
+% parenthetical citation is provided. Except for the fact that his style
+% works with version~0.99 of \btx, its functionality is identical to that
+% of the \texttt{natsci} files.
+%
+% Patashnik does not like author--year citations. He makes this very clear
+% in his \btx{} manuals and in the header to \texttt{apalike.bst}.
+% Nevertheless, one should respect his work in this area, simply because he
+% should be the best expert on matters of \btx. Thus \texttt{apalike.bst}
+% could be the basis for other styles.
+%
+% The form of the \texttt{thebibliography} entries in this system is
+% \begin{quote}
+% |\bibitem[Jones et al., 1990]{jon90}...|
+% \end{quote}
+% the same as I illustrated earlier. This is the most minimal form that can
+% be given. I name it the \texttt{apalike} variant, after Patashnik's
+% \texttt{apalike.bst} and \texttt{apalike.sty}. However, there could be many
+% independent \texttt{.bst} files that follow this line.
+%
+% The bibliography style files belonging to this group include:
+% \begin{quote}
+% \texttt{apalike}, \texttt{apalike2}, \texttt{cea}, \texttt{cell},
+% \texttt{jmb}, \texttt{phapalik}, \texttt{phppcf}, \texttt{phrmp}
+% \end{quote}
+%
+% \subsection{The \texttt{newapa} Style}
+% A major improvement has been achieved with \texttt{newapa.bst} and the
+% accompanying \texttt{newapa.sty} files by Stephen N. Spencer and Young U.
+% Ryu. Under their system, three separate items of information are included
+% in the |\bibitem| label, to be used as required. These are: the full
+% author list, the abbreviated list, and the year. This is accomplished by
+% means of a |\citeauthoryear| command included in the label, as
+% \begin{quote}
+% |\bibitem[\protect\citeauthoryear{Jones, Barker,|\\
+% | and Williams}{Jones et al.}{1990}]{jon90}...|
+% \end{quote}
+% Actually, this only illustrates the basic structure of |\citeauthoryear|;
+% the \texttt{newapa} files go even further to replace some words and
+% punctuation
+% with commands. For example, the word `and' above is really
+% |\betweenauthors|, something that must be defined in the \texttt{.sty} file.
+% Of course, |\citeauthoryear| is also defined in that file. A
+% number of different |\cite| commands are available to print out the
+% citation with complete author list, with the short list, with or without
+% the date, the textual or parenthetical form.
+%
+% Thus the |\citeauthoryear| entry in |\bibitem| is very flexible,
+% permitting the style file to generate every citation form that one might
+% want. It is used by a number of other styles, with corresponding
+% \texttt{.sty} files. They all appear to have been inspired by
+% \texttt{newapa.bst}, although they lack the extra punctuation commands.
+%
+% Bibliographic style files belonging to the \texttt{newapa} group include
+% \begin{quote}
+% \texttt{newapa}, \texttt{chicago}, \texttt{chicagoa}, \texttt{jas99},
+% \texttt{named}
+% \end{quote}
+% Note: the last of these, \texttt{named.bst}, uses |\citeauthoryear| in a
+% slightly different manner, with only two arguments: the short list and
+% year.
+%
+% \subsection{The Harvard Family}
+% The same effect is achieved by a different approach in the Harvard family
+% of bibliographic styles. Here a substitute for |\bibitem| is used, as
+% \begin{quote}
+% |\harvarditem[Jones et al.]{Jones, Baker, and|\\
+% | Williams}{1990}{jon90}...|
+% \end{quote}
+% The accompanying interface package file is called \texttt{harvard.sty}
+% and is written by Peter Williams and Thorsten Schnier. It
+% defines |\harvarditem| as well as the citation commands |\cite|, for
+% parenthentical, and |\citeasnoun|, for textual citations. The first
+% citation uses the long author list, following ones the shorter list, if
+% it has been given in the optional argument to |\harvarditem|.
+%
+% Bibliography styles belonging to the Harvard family are
+% \begin{quote}
+% \texttt{agsm}, \texttt{dcu}, \texttt{kluwer}
+% \end{quote}
+%
+% This package has been updated for \LaTeXe, with many additions to
+% add flexibility. The result is a powerful interface that should meet most
+% citation needs. (It does not suppress repeated authors, though,
+% as \thestyle{} does.)
+%
+% \subsection{The Astronomy Style}
+% Apparently realizing the limitations of his \texttt{apalike} system, Oren
+% Patashnik went on to develop a `true' \texttt{apa} bibliographic style,
+% making use of the method already employed by an astronomy journal. This
+% is actually very similar to the \texttt{newapa} label but with only the
+% short list of authors:
+% \begin{quote}
+% |\bibitem[\protect\astroncite{Jones et al.}{1990}]{jon90}|\\
+% | ...|
+% \end{quote}
+% It requires the package file \texttt{astron.sty}
+% or any other style that defines |\astroncite| appropriately.
+%
+% Bibliographic styles belonging to the astronomy group are
+% \begin{quote}
+% \texttt{apa}, \texttt{astron}, \texttt{bbs}, \texttt{cbe},
+% \texttt{humanbio}, \texttt{humannat}, \texttt{jtb}
+% \end{quote}
+%
+% This is as good as the |\citeauthoryear| command, although not as
+% flexible since the full list of authors is missing.
+%
+% \subsection{The \texttt{authordate} Style}
+% Finally, I have also found some packages making use of a label command
+% called |\citename| in the form
+% \begin{quote}
+% |\bibitem[\protect\citename{Jones et al., }1990]{jon90}|\\
+% | ...|
+% \end{quote}
+%
+% This is not a good system since the author list and date are not cleanly
+% separated as individual arguments, and since the punctuation is included
+% in the label text. It is better to keep the punctuation fully removed, as
+% part of the definitions in the \texttt{.sty} file, for complete flexibility.
+%
+% Bibliographic styles belonging to this group are
+% \begin{quote}
+% \texttt{authordate1}, \texttt{authordate2}, \texttt{authordate3},
+% \texttt{authordate4}, \texttt{aaai-named}
+% \end{quote}
+% with accompanying style file \texttt{authordate1-4.sty}.
+%
+% \section{The \thestyle{} System}
+% The form of the |\bibitem| entry that I have used for all my
+% bibliographic styles is only slightly more complicated than the minimal
+% one, but allows a clean separation between authors and date:
+% \begin{quote}
+% |\bibitem[Jones et al.(1990)]{jon90}...|\\[1ex]
+% or alternatively\\[1ex]
+% |\bibitem[Jones et al.(1990)Jones, Baker, |\\
+% \hspace*{2em}|and Williams]{jon90}...|
+% \end{quote}
+%
+% (One weakness of the \thestyle{} format is that it fails if the author
+% list itself contains parentheses! This may be fixed up if the author list
+% is grouped in curly braces.)
+%
+% I wanted to name the system something like `natural sciences bibliography',
+% intending it to be a variant of \texttt{natsci.sty}. Since that name
+% was already taken, I resorted to the rather cryptic, and definitely ugly,
+% \thestyle.
+%
+% The \thestyle\texttt{.sty} package\footnote{Formerly called a \emph{style
+% file} in the older \LaTeX~2.09 terminology.} supports not only my own
+% |\bibitem| format, but also all the others described here, plus numerical
+% citation modes. The additional questions of citation style (type of brackets,
+% commas or semi-colons between citations) can be defined once and for all for
+% each \texttt{.bst} file and need never be specified explicitly in the source
+% text. The |\cite| commands and syntax are always those of \thestyle, even
+% when used with a \texttt{.bst} file such as \texttt{chicago.bst} that would
+% normally have a different set of commands (defined in \texttt{chicago.sty}).
+% The result is a single \LaTeX{} package to handle {\em all\/} the
+% bibliographic styles in a uniform manner.
+%
+% All the author--year bibliographic style files can also be used for
+% \emph{numerical} citations, by simply selecting the mode in one of the
+% ways described in Sections~\ref{sec:bibpunct} and \ref{sec:opts}. It is
+% not possible to employ author-year citations with pure numerical
+% \texttt{.bst} files, and never will be.
+% See Section~\ref{sec:6.0} for more information.
+%
+% \section{Using this Package}\label{sec:usage}
+%
+% \iffalse
+%<*notes>
+\head{Loading}
+Load with |\usepackage[|\emph{options}|]{|\thestyle|}|. See list of
+\emph{options} at the end.
+
+%</notes>
+% \fi
+% In this paper, I distinguish between the citation \emph{mode} (author--year
+% or numerical) and citation \emph{style} (the type of punctuation used for
+% citations). The citation style is something that is independent of the
+% bibliography style and is not programmed in the \texttt{.bst} files.
+%
+% \subsection{New Bibliography Styles}\label{sec:plainnat}
+%
+% \iffalse
+%<*notes>
+\head{Replacement bibliography styles}
+% \fi
+I provide three new \texttt{.bst} files to replace the standard \LaTeX\
+numerical ones:
+\begin{quote}\ttfamily
+ plainnat.bst \qquad abbrvnat.bst \qquad unsrtnat.bst
+\end{quote}
+% \iffalse
+%</notes>
+% \fi
+% These produce reference lists in the same style as the corresponding
+% standard \texttt{.bst} file, but work with \thestyle{}. The
+% advantage is that they can be used in both numerical and author--year
+% mode.
+%
+% These \texttt{.bst} files are not meant to be exhaustive by any means. Other
+% style files conforming to the \thestyle{} format exist, or may be generated
+% with my \texttt{custom-bib} (also known as \texttt{makebst}) program.
+%
+% \subsection{Basic Citation Commands}
+%
+% \DescribeMacro{\citet}
+% \DescribeMacro{\citep}
+% \iffalse
+%<*notes>
+\head{Basic commands}
+% \fi
+The \thestyle\ package has two basic citation commands, |\citet| and
+|\citep| for \emph{textual} and \emph{parenthetical} citations, respectively.
+There also exist the starred versions |\citet*| and |\citep*| that print
+the full author list, and not just the abbreviated one.
+All of these may take one or two optional arguments to add some text before
+and after the citation.
+\begin{quote}
+\begin{tabular}{l@{\quad$\Rightarrow$\quad}l}
+ |\citet{jon90}| & Jones et al. (1990)\\
+ |\citet[chap.~2]{jon90}| & Jones et al. (1990, chap.~2)\\[0.5ex]
+ |\citep{jon90}| & (Jones et al., 1990)\\
+ |\citep[chap.~2]{jon90}| & (Jones et al., 1990, chap.~2)\\
+ |\citep[see][]{jon90}| & (see Jones et al., 1990)\\
+ |\citep[see][chap.~2]{jon90}| & (see Jones et al., 1990, chap.~2)\\[0.5ex]
+ |\citet*{jon90}| & Jones, Baker, and Williams (1990)\\
+ |\citep*{jon90}| & (Jones, Baker, and Williams, 1990)
+\end{tabular}
+\end{quote}
+% \iffalse
+%</notes>
+% \fi
+% The starred versions can only list the full authors if the \texttt{.bst}
+% file supports this feature; otherwise, the abbreviated list is printed.
+%
+% In standard \LaTeX, the |\cite| command can only take a single optional
+% text for a note after the citation; here, a single optional text is a
+% post-note, while two are the pre- and post-notes. To have only a pre-note, it
+% is necessary to provide an empty post-note text, as shown above.
+%
+% More complex mixtures of text and citations can be generated with the
+% all-purpose |\citetext| command in Section~\ref{sec:excite}.
+%
+% \iffalse
+%<*notes>
+\head{Multiple citations}
+% \fi
+Multiple citations may be made by including more than one
+citation key in the |\cite| command argument.
+% \textsl{If adjacent citations
+% have the same author designation but different years, then the author
+% names are not reprinted.}
+\begin{quote}
+\begin{tabular}{l@{\quad$\Rightarrow$\quad}l}
+ |\citet{jon90,jam91}| & Jones et al. (1990); James et al. (1991)\\
+ |\citep{jon90,jam91}| & (Jones et al., 1990; James et al. 1991)\\
+ |\citep{jon90,jon91}| & (Jones et al., 1990, 1991)\\
+ |\citep{jon90a,jon90b}| & (Jones et al., 1990a,b)
+\end{tabular}
+\end{quote}
+
+% \iffalse
+\head{Numerical mode}
+% \fi
+These examples are for author--year citation mode. In numerical mode, the
+results are different.
+\begin{quote}
+\begin{tabular}{l@{\quad$\Rightarrow$\quad}l}
+ |\citet{jon90}| & Jones et al. [21]\\
+ |\citet[chap.~2]{jon90}| & Jones et al. [21, chap.~2]\\[0.5ex]
+ |\citep{jon90}| & [21]\\
+ |\citep[chap.~2]{jon90}| & [21, chap.~2]\\
+ |\citep[see][]{jon90}| & [see 21]\\
+ |\citep[see][chap.~2]{jon90}| & [see 21, chap.~2]\\[0.5ex]
+ |\citep{jon90a,jon90b}| & [21, 32]
+\end{tabular}
+\end{quote}
+% \iffalse
+%</notes>
+% \fi
+% The authors can only be listed if the \texttt{.bst} file supports
+% author--year citations. The standard \texttt{.bst} files, such as
+% \texttt{plain.bst} are numerical only and transfer no author--year
+% information to \LaTeX. In this case, |\citet| prints ``\textbf{(author?)}
+% [21].''
+%
+% \DescribeMacro{\cite}
+% In the original versions of \thestyle, the traditional |\cite| command was
+% used for both textual and parenthetical citations. The presence of an empty
+% optional text in square brackets signalled parenthetical. This syntax has been
+% retained for compatibility, but is no longer encouraged.
+%
+% This means that |\cite| (without notes) is the same as |\citet| in
+% author--year mode, whereas in numerical mode, it is the same as |\citep|.
+% The starred version, as well as the one or two optional notes, may also be
+% used.
+%
+% It is possible to have multiple citations sorted into the same sequence as
+% they appear in the list of references, regardless of their order as
+% arguments to the |\cite| commands. The option \texttt{sort} is required for
+% this feature. See Section~\ref{sec:sort}.
+%
+% Some publishers require that the first citation of any given reference be
+% given with the full author list, but that all subsequent ones with the
+% abbreviated list. Include the option \texttt{longnamesfirst} to enable this for
+% \thestyle. See Section~\ref{sec:long}.
+%
+% \subsection{Extended Citation Commands}
+% \label{sec:excite}
+%
+% \DescribeMacro{\citealt}
+% \DescribeMacro{\citealp}
+% \DescribeMacro{\citetext}
+% \iffalse
+%<*notes>
+\head{Suppressed parentheses}
+% \fi
+As an alternative form of citation, |\citealt| is the same as |\citet| but
+\emph{without parentheses}. Similarly, |\citealp| is |\citep| without
+parentheses. Multiple references, notes, and the starred variants
+also exist.
+\begin{quote}
+\begin{tabular}{l@{\quad$\Rightarrow$\quad}l}
+ |\citealt{jon90}| & Jones et al.\ 1990\\
+ |\citealt*{jon90}| & Jones, Baker, and Williams 1990\\
+ |\citealp{jon90}| & Jones et al., 1990\\
+ |\citealp*{jon90}| & Jones, Baker, and Williams, 1990\\
+ |\citealp{jon90,jam91}| & Jones et al., 1990; James et al., 1991\\
+ |\citealp[pg.~32]{jon90}| & Jones et al., 1990, pg.~32\\
+ |\citetext{priv.\ comm.}| & (priv.\ comm.)
+\end{tabular}
+\end{quote}
+The |\citetext| command
+allows arbitrary text to be placed in the current citation parentheses.
+This may be used in combination with |\citealp|.
+% For example,
+% \begin{verbatim}
+% \citetext{see \citealp{jon90},
+% or even better \citealp{jam91}}
+% \end{verbatim}
+% to produce (see Jones et al., 1990, or even better James et al., 1991).
+%
+% \iffalse
+%</notes>
+% \fi
+%
+% \DescribeMacro{\citeauthor}
+% \DescribeMacro{\citeyear}
+% \DescribeMacro{\citeyearpar}
+% \DescribeMacro{\citefullauthor}
+% \iffalse
+%<*notes>
+\head{Partial citations}
+% \fi
+In author--year schemes, it is sometimes desirable to be able to refer to
+the authors without the year, or vice versa. This is provided with the
+extra commands
+\begin{quote}
+\begin{tabular}{l@{\quad$\Rightarrow$\quad}l}
+ |\citeauthor{jon90}| & Jones et al.\\
+ |\citeauthor*{jon90}| & Jones, Baker, and Williams\\
+ |\citeyear{jon90}| & 1990\\
+ |\citeyearpar{jon90}| & (1990)
+\end{tabular}
+\end{quote}
+% \iffalse
+%</notes>
+% \fi
+% There also exists a command |\citefullauthor| which is equivalent to
+% |\citeauthor*|.
+%
+% If the full author information is missing, then |\citeauthor*| is
+% the same as |\citeauthor|, printing only the abbreviated list.
+% This also applies to the starred versions of |\citet| and |\citep|.
+%
+% If the author or year information is missing (as is the case with the
+% standard \LaTeX{} \texttt{.bst} files), these commands issue a warning.
+%
+% \medskip\noindent
+% \textbf{Note:}
+% these commands may also be used with numerical
+% citations, provided an author--year \texttt{.bst} file is being employed.
+%
+% \medskip\noindent
+% \textbf{Note:} all |\cite..| commands have the same
+% syntax, allowing multiple citations and up to two notes (there is, however,
+% no starred |\citeyear| variant). It does not really make much sense to add
+% notes to |\citeyear| and |\citeauthor|, especially with multiple citations;
+% however, this can be done, there will be no error message, but the results
+% are sometimes strange. For example, in numerical mode, the notes are fully
+% ignored, while in author--year mode, only the post-note is accepted.
+% Multiple citations in |\citet| are also not recommended (nor are they in my
+% opinion meaningful), but if they are used with notes, the pre-note will
+% appear before each year, and the post-note only after the last year. These
+% are admittedly bugs, but the effort to remove them is not justified by the
+% questionable usefulness of these features.
+%
+% In summary, notes are only intended for |\citep| but they may also be used
+% with |\citet| in author--year mode, with single citations. In any other
+% situation, the results are unpredictable.
+%
+% \DescribeMacro{\Citet}
+% \DescribeMacro{\Citep}
+% \DescribeMacro{\Citealt}
+% \DescribeMacro{\Citealp}
+% \DescribeMacro{\Citeauthor}
+% \subsection{Forcing Upper Cased Name}
+% \iffalse
+%<*notes>
+\head{Forcing upper cased names}
+% \fi
+If the first author's name contains a \textsl{von} part, such as ``della
+Robbia'', then |\citet{dRob98}| produces ``della Robbia (1998)'', even at the
+beginning of a sentence. One can force the first letter to be in upper case
+with the command |\Citet| instead. Other upper case commands also exist.
+\begin{quote}
+\begin{tabular}{rl@{\quad$\Rightarrow$\quad}l}
+ when & |\citet{dRob98}| & della Robbia (1998) \\
+ then & |\Citet{dRob98}| & Della Robbia (1998) \\
+ & |\Citep{dRob98}| & (Della Robbia, 1998) \\
+ & |\Citealt{dRob98}| & Della Robbia 1998 \\
+ & |\Citealp{dRob98}| & Della Robbia, 1998 \\
+ & |\Citeauthor{dRob98}| & Della Robbia
+\end{tabular}
+\end{quote}
+These commands also exist in starred versions for full author names.
+
+% \textbf{Note:} the coding for the upper casing commands is tricky and likely
+% buggy. It operates on the names that are stored in the |\bibitem| entry, and
+% works even if old style font commands are used; however, NFSS commands will
+% cause it to crash. Thus
+% \begin{tabular}{ll}
+% |\bibitem[{\it della Robbia}(1998)]{dRob98}| & is okay, but \\
+% |\bibitem[\textit{della Robbia}(1998)]{dRob98}| & crashes.
+% \end{tabular}
+% I hope to improve this situation in future.
+%
+% \iffalse
+%</notes>
+% \fi
+%
+% \subsection{Citation Aliasing}
+% \DescribeMacro{\defcitealias}
+% \DescribeMacro{\citetalias}
+% \DescribeMacro{\citepalias}
+% \iffalse
+%<*notes>
+\head{Citation aliasing}
+% \fi
+Sometimes one wants to refer to a reference with a special designation,
+rather than by the authors, i.e. as Paper~I, Paper~II. Such aliases can be
+defined and used, textual and/or parenthetical with:
+\begin{quote}
+\begin{tabular}{lcl}
+ |\defcitealias{jon90}{Paper~I}|\\
+ |\citetalias{jon90}| & $\Rightarrow$ & Paper~I\\
+ |\citepalias{jon90}| & $\Rightarrow$ & (Paper~I)
+\end{tabular}
+\end{quote}
+These citation commands function much like |\citet| and |\citep|: they may
+take multiple keys in the argument, may contain notes, and are marked as
+hyperlinks.
+% \iffalse
+%</notes>
+% \fi
+%
+% A warning is issued if the alias is used before it is defined, or if an alias
+% is redefined for a given citation. No warning is issued if an alias is
+% defined for a citation key that does not exist; the warning comes when it is
+% used!
+%
+% See Section~\ref{sec:yearless} for an alternative means of citing with
+% a code name.
+%
+% \subsection{Authorless and Yearless References}\label{sec:yearless}
+% What does one do about references that do not have authors? This has long
+% bothered me but I do have a suggestion. Standard \btx\ styles make use of a
+% \texttt{KEY} field in the entries to be used for alphabetizing when the
+% authors or editors are missing. The author--year styles go even further and
+% insert the \texttt{KEY} field in place of the authors. One can imagine giving
+% a code designation for the work at this point. For example,
+% \begin{quote}
+% \begin{verbatim}
+% @MANUAL{handbk98,
+% title = {Assembling Computers},
+% year = 1998,
+% organization = {MacroHard Inc.},
+% key = "MH-MAN"
+% }
+% \end{verbatim}
+% \end{quote}
+% With \texttt{plain}, the key text \texttt{MH-MAN} is used only to order the
+% reference, but with \texttt{plainnat} and other author--year styles, it is
+% used in place of the authors. One can then refer to it as
+% |\citeauthor{handbk98}| to get MH-MAN or as |\citetext{\citeauthor{handbk98}}|
+% for (MH-MAN), a parenthetical citation.
+%
+% This can be greatly simplified if
+% the bibliography style leaves the date blank in the |\bibitem|
+% entry, as
+% \begin{quote}
+% |\bibitem[MH-MAN()]{handbk98}|
+% \end{quote}
+% for then \thestyle\ suppresses the date, preceding punctuation, and the
+% braces for |\citet|. This means that |\citet| and |\citep| behave
+% automatically like the two examples above.
+% The date still may appear in the text of the reference.
+%
+% The \thestyle\ bibliography styles have been modified accordingly to omit
+% the date from the |\bibitem| entry when missing authors and/or editors
+% are replaced by key text.
+%
+% Similarly, if the year is missing, it will be left blank in the |\bibitem|
+% entry; thus citing such a work will only produce the authors' names.
+%
+% \textbf{Note:} there are many other possibilities with this feature. One can
+% even produce citations like those of the \texttt{alpha} bibliography style,
+% by placing the citation code in place of the authors in the |\bibitem| entry
+% and leaving the year blank. A second code (or maybe even the authors
+% themselves) could be placed where the full author list normally appears, to
+% be printed with the starred version of the |\cite| commands. For example,
+% \begin{quote}
+% |\bibitem[MH-MAN()MacroHard Inc.]{handbk98}|
+% \end{quote}
+%
+% \subsection{Extra Features in the \texttt{plainnat} Family}\label{sec:url}
+%
+% The special \texttt{.bst} files for \thestyle\ mentioned in
+% Section~\ref{sec:plainnat} have a number of extra fields compared to the
+% original files: \\
+% \begin{tabular}{ll}
+% \texttt{ISBN} & for the ISBN number in books,\\
+% \texttt{ISSN} & for the ISSN number in periodicals,\\
+% \texttt{URL} & for the Internet address of on-line documents.
+% \end{tabular}
+% The URL address is set in a typewriter font and often leads to line-breaking
+% problems. It is advisable to load the \texttt{url} package of Donald
+% Arseneau, which allows typewriter text to be broken at punctuation marks. The
+% URL addresses are set with the |\url| command in this package, but if it is
+% not loaded, then |\url| is defined to be |\texttt|, with no line breaks.
+%
+% As pointed out in Section~\ref{sec:yearless}, the \texttt{KEY} field is
+% treated differently by \texttt{plainnat} than in \texttt{plain}. Whereas the
+% latter uses this field only to alphabetize entries without authors,
+% \texttt{plainnat} actually inserts it in place of the author, both in the
+% reference text and in the citation label (|\bibitem| entries). Furthermore,
+% the year is left empty in |\bibitem| so that |\citep| prints only the
+% ``author'' text, which is now the \texttt{KEY}. This should be some code
+% designation for the work.
+%
+% \subsection{Selecting Citation Punctuation}\label{sec:bibpunct}
+%
+% \DescribeMacro{\bibpunct}
+% The above examples have been printed with the default citation style.
+% It is possible to change this, as well as to select numerical or
+% author--year mode, by means of the |\bibpunct| command, which takes
+% one optional and 6 mandatory arguments. The mandatory ones are:
+% \iffalse
+%<*notes>
+\head{Selecting citation style and punctuation}
+Use the command |\bibpunct| with one optional and 6 mandatory arguments:
+% \fi
+\begin{enumerate}
+\item the opening bracket symbol, default = (
+\item the closing bracket symbol, default = )
+\item the punctuation between multiple citations, default = ;
+\item the letter `n' for numerical style, or `s' for numerical superscript
+ style, any other letter for
+ author--year, default = author--year;
+% note, it is not necessary to
+% specify which author--year interface is being used, for all will be
+% recognized;
+\item the punctuation that comes between the author names and the year
+% (parenthetical case only), default = ,
+\item the punctuation that comes between years or numbers when common author
+ lists are suppressed (default = ,);
+% if both authors and years are
+% common, the citation is printed as `1994a,b', but if a space
+% is wanted between the extra letters, then include the space
+% in the argument, as |{,~}|.
+%
+% For numerical mode, |\citet{jon90,jon91}| produces
+% `Jones et al.\ [21, 22]' with this punctuation between the numbers.
+% A space is automatically included for numbers, but not for
+% superscripts.
+%
+\end{enumerate}
+
+The optional argument is the character preceding a post-note, default is a
+comma plus space. In redefining this character, one must include a space if
+one is wanted.
+
+% The |\bibpunct| command must be issued in the preamble, that is,
+% before |\begin{document}|.
+%
+Example~1, |\bibpunct{[}{]}{,}{a}{}{;}| changes the output of
+\begin{quote}
+ |\citep{jon90,jon91,jam92}|
+\end{quote}
+into [Jones et al. 1990; 1991, James et al. 1992].
+
+Example~2, |\bibpunct[; ]{(}{)}{,}{a}{}{;}| changes the output of
+\begin{quote}
+ |\citep[and references therein]{jon90}|
+\end{quote}
+into (Jones et al. 1990; and references therein).
+
+% \iffalse
+%</notes>
+% \fi
+%
+% \DescribeMacro{\bibstyle@xxx}
+% Usually the citation style is determined by the journal
+% for which one is writing, and is as much a part of the bibliography style
+% as everything else. The \thestyle{} package allows
+% punctuation definitions to be directly coupled to the
+% |\bibliographystyle| command that must always be present when \btx{} is
+% used. It is this command that selects the \texttt{.bst} file; by adding such
+% a coupling to \thestyle{} for every \texttt{.bst} file that one might
+% want to use, it is not necessary to add |\bibpunct| explicitly in the
+% document itself, unless of course one wishes to override the preset
+% values.
+%
+% Such a coupling is achieved by defining a command |\bibstyle@|{\em bst},
+% where {\em bst\/} stands for the name of the \texttt{.bst} file. For example,
+% the American Geophysical Union (AGU) demands in its publications that
+% citations be made with square brackets and separated by semi-colons. I
+% have an \texttt{agu.bst} file to accomplish most of the formatting, but such
+% punctuations are not included in it. Instead, \thestyle{} has the
+% definition
+% \begin{quote}
+% |\newcommand{\bibstyle@agu}{\bibpunct{[}{]}{;}{a}{,}{,~}}|
+% \end{quote}
+%
+% These style defining commands may contain more than just |\bibpunct|.
+% Some numerical citation scheme require even more changes. For example,
+% the journal \textsl{Nature} not only uses superscripted numbers for
+% citations, it also prints the numbers in the list of references without
+% the normal square brackets. To
+% accommodate this, \thestyle{} contains the style definition
+% \begin{quote}\begin{verbatim}
+% \newcommand{\bibstyle@nature}%
+% {\bibpunct{}{}{,}{s}{}{\textsuperscript{,}}%
+% \gdef\NAT@biblabelnum##1{##1.}}
+% \end{verbatim}
+% \end{quote}
+% The redefined |\NAT@biblabelnum| command specifies how the reference numbers
+% are to be formatted in the list of references itself.
+% The redefinition must be made with |\gdef|, not |\def| or
+% |\renewcommand|.
+%
+% The selected punctuation style and other redefinitions will not be in
+% effect on the first \LaTeX{} run, for they are stored to the auxiliary
+% file for the subsequent run.
+%
+% The user may add more such definitions of his own, to accommodate those
+% journals and \texttt{.bst} files that he has. He may either add them to
+% his local copy of \thestyle\texttt{.sty}, or better put them into a file
+% named \thestyle\texttt{.cfg}. This file will be read in if it exists,
+% adding any local configurations. Thus such configurations can survive
+% future updates of the package. (This is for \LaTeXe{} only.)
+%
+% \medskip
+% \noindent\textbf{Note:}
+% any explicit call to |\bibpunct| has priority over the
+% predefined citation styles.
+%
+% \DescribeMacro{\citestyle}
+% A preprogrammed citation style is normally invoked by the command
+% |\bibliographystyle|, as described above. However, it may be that one wants
+% to apply a certain citation style to another bibliography style. This may be
+% done with |\citestyle|, given \emph{before} |\begin{document}|. For example,
+% to use the \texttt{plainnat} bibliography style (for the list of references)
+% with the \textsl{Nature} style of citations (superscripts),
+% \begin{quote}
+% |\documentclass{article}|\\
+% |\usepackage{|\thestyle|}|\\
+% |. . . . .|\\
+% |\citestyle{nature}|\\
+% |\begin{document}|\\
+% |\bibliographystyle{plainnat}|\\
+% |. . . . .|
+% \end{quote}
+%
+% \noindent
+% \textbf{Note:} all changes to the citation
+% style, including punctuation, must be made before |\begin{document}|,
+% which freezes the citation style.
+%
+% \subsection{Priority of Style Commands}\label{sec:priority}
+% The citation style (punctuation and mode) can be selected by means of the
+% |\bibpunct|, |\citestyle|, and predefined |\bibstyle@|\textit{bst}
+% commands. They can also be selected by \LaTeXe{} options
+% (Section~\ref{sec:opts}). What happens if there are several conflicting
+% selections?
+%
+% The lowest priority is assigned to the predefined |\bibstyle@|\textit{bst}
+% commands, since they are implicit and not obvious to the user. The
+% \LaTeXe{} options have the next priority. Finally, any selection by
+% |\bibpunct| and/or |\citestyle| overrides those of the other methods.
+%
+% \subsection{Other Formatting Options}
+%
+% \iffalse
+%<*notes>
+\head{Other formatting options}
+% \fi
+%
+% \DescribeMacro{\bibsection}
+% The list of references normally appears as a |\section*| or |\chapter*|,
+% depending on the main class. If one wants to redesign one's own heading,
+% say as a numbered section with |\section|, then |\bibsection| may be
+% redefined by the user accordingly.
+%
+% \iffalse
+Redefine |\bibsection| to the desired sectioning command for introducing
+the list of references. This is normally |\section*| or |\chapter*|.
+
+% \fi
+%
+% \DescribeMacro{\bibpreamble}
+% A preamble appearing after the |\bibsection| heading may be inserted before
+% the actual list of references by defining |\bibpreamble|. This will appear in
+% the normal text font unless it contains font declarations. The
+% |\bibfont| applies to the list of references, not to this preamble.
+%
+% \iffalse
+Define |\bibpreamble| to be any text that is to be printed after the heading but
+before the actual list of references.
+
+% \fi
+%
+% \DescribeMacro{\bibfont}
+% The list of references is normally printed in the same font size and
+% style as the main body. However, it is possible to define |\bibfont|
+% to be font commands that are in effect within the \texttt{thebibliography}
+% environment after any preamble. For example,
+% \begin{quote}
+% |\newcommand{\bibfont}{\small}|
+% \end{quote}
+% \iffalse
+Define |\bibfont| to be a font declaration, e.g.\ |\small| to apply to
+the list of references.
+
+% \fi
+%
+% \DescribeMacro{\citenumfont}
+% Numerical citations may be printed in a different font. Define |\citenumfont|
+% to be a font declaration like |\itshape| or even a command taking arguments
+% like |\textit|.
+% \begin{quote}
+% |\newcommand{\citenumfont}[1]{\textit{#1}}|
+% \end{quote}
+% The above is better than |\itshape| since it automatically adds italic
+% correction.
+% \iffalse
+Define |\citenumfont| to be a font declaration or command like |\itshape|
+or |\textit|.
+
+% \fi
+%
+% \DescribeMacro{\bibnumfmt}
+% The format of the numerical listing in the reference list may also be changed
+% from the default [32] by redefining |\bibnumfmt|, for example
+% \begin{quote}
+% |\renewcommand{\bibnumfmt}[1]{\textbf{#1}:}|
+% \end{quote}
+% to achieve \textbf{32}: instead.
+% \iffalse
+Redefine |\bibnumfmt| as a command with an argument to format the numbers in
+the list of references. The default definition is |[#1]|.
+
+% \fi
+%
+% \DescribeMacro{\bibhang}
+% The list of references for author--year styles uses a hanging indentation
+% format: the first line of each reference is flush left, the following lines
+% are set with an indentation from the left margin. This indentation is 1~em
+% by default but may be changed by redefining (with |\setlength|) the
+% length parameter |\bibhang|.
+%
+% \iffalse
+The indentation after the first line of each reference is given by
+|\bibhang|; change this with the |\setlength| command.
+
+% \fi
+% \DescribeMacro{\bibsep}
+% The vertical spacing between references in the list, whether author--year
+% or numerical, is controlled by the length |\bibsep|. If this is set to
+% 0~pt, there is no extra line spacing between references. The default
+% spacing depends on the font size selected in |\documentclass|, and is
+% almost a full blank line. Change this by redefining |\bibsep| with
+% |\setlength| command.
+%
+% \iffalse
+The vertical spacing between references is set by |\bibsep|; change this with
+the |\setlength| command.
+
+%</notes>
+% \fi
+%
+% \subsection{Automatic Indexing of Citations}
+%
+% \DescribeMacro{\citeindextrue}
+% \DescribeMacro{\citeindexfalse}
+% \iffalse
+%<*notes>
+\head{Automatic indexing of citations}
+% \fi
+If one wishes to have the citations entered in the \texttt{.idx} indexing
+file, it is only necessary to issue |\citeindextrue| at any point in the
+document. All following |\cite| commands, of all variations, then insert
+the corresponding entry to that file. With |\citeindexfalse|, these
+entries will no longer be made.
+
+% \iffalse
+%</notes>
+% \fi
+% The |\bibitem| commands in the \texttt{thebibliography} environment will
+% also make index entries. If this is not desired, then issue
+% |\citeindexfalse| before |\bibliography| or |\begin{thebibliography}|.
+%
+% Of course, |\makeindex| must also be issued in the preamble to activate
+% indexing, as usual. Otherwise, no indexing is done at all.
+%
+% Make sure that the document has been processed at least twice after the
+% last \btx\ run before running the \texttt{makeindex} program.
+%
+% \DescribeMacro{\NAT@idxtxt}
+% The form of the index entries is set by the internal |\NAT@idxtxt|, which
+% can be redefined by hackers if wanted (in the \thestyle\texttt{.cfg} file
+% please). By default, it prints the short author list plus date in the
+% current parenthesis style.
+%
+% The \thestyle\ package can also be used with the \texttt{index} package of
+% David~M. Jones. The order in which the packages are loaded is not
+% important.
+%
+% \DescribeMacro{\citeindextype}
+% In that package, multiple index lists may be made by means of a |\newindex|
+% command. For example, it may be desirable to put all the citation indexing
+% into a separate list. First that list must be initiated with, e.g.,
+% \begin{quote}
+% |\newindex{cite}{ctx}{cnd}{List of Citations}|
+% \end{quote}
+% and then the automatic citation indexing associated with this list with the
+% \thestyle\ command
+% \begin{quote}
+% |\renewcommand{\citeindextype}{cite}|
+% \end{quote}
+% See the documentation for \texttt{index.sty} for details.
+%
+% \subsection{Hyper\TeX\ Compatibility}
+% The \thestyle\ package is compatible with the \texttt{hyperref}
+% package of Sebastian Rahtz
+% , for use with
+% \LaTeX\ $\rightarrow$ HTML conversions, pdf\TeX, \texttt{pdfmark}.
+% The compatibility is of a mutual nature: both packages contain
+% coding that interact with that of the other.
+%
+% There is a special option \texttt{nonamebreak} that can be used with the
+% \texttt{hyperref} package; it keeps all the author names in a citation on one
+% line, something that avoids certain problems with pdf\TeX. This is otherwise
+% not recommended, since many overfull lines result.
+%
+% \subsection{Multiple Bibliographies in One Document}\label{sec:chapbib}
+%
+% \iffalse
+%<*notes>
+\head{Use with \texttt{chapterbib} package}
+% \fi
+
+The \thestyle\ package is compatible with the \texttt{chapterbib} package
+% of Donald Arseneau and Niel Kempson,\relax
+% \footnote{I have used version 1.5 from 1995/10/09; cannot guarantee
+% earlier versions.}
+which makes it possible to have several bibliographies in one document.
+% The usual application is to have bibliographies in each chapter of a book,
+% especially if they have been written by different authors.
+%
+% The \texttt{chapterbib} package works in a very natural way for the
+% author; only the editor who puts all the chapters together into one book
+% has to do some extra work.
+
+The package makes use of the |\include| command, and each |\include|d file
+has its own bibliography.
+% For large books, it makes very good sense to take advantage of this feature
+% in any case.
+%
+% To review the use of |\include|, recall that the main file
+% \begin{verbatim}
+% \documentclass{...}
+% \includeonly{ch2}
+% \begin{document}
+% \include{ch1}
+% \include{ch2}
+% \include{ch3}
+% \end{document}
+% \end{verbatim}
+% will process only the file \texttt{ch2.tex} as though the files
+% \texttt{ch1.tex} and \texttt{ch3.tex} were also present. That is, all
+% counters, especially the page and section numbers, as well as
+% cross-referencing definitions, will function as if the whole document
+% were processed. The trick is that each |\include|d file has it own
+% \texttt{.aux} file containing these definitions, and they are all read
+% in every time, even if the corresponding \texttt{.tex} file is not. The
+% \texttt{.aux} files also contain the citation information for \btx,
+% something that the \texttt{chapterbib} package exploits.
+%
+% If |\usepackage{chapterbib}| has been given, the keys in each |\cite|
+% and |\bibitem| command are associated with the current |\include|d file
+% and are distinguished from the identical key in a different file. Each of
+% these files must contain its own |\bibliography| and |\bibliographystyle|
+% commands. One processes \btx\ on each file separately before processing
+% it under \LaTeX\ (at least twice).
+%
+% \subsubsection{Special Considerations for \thestyle\ and
+% \texttt{chapterbib}}
+
+The order in which the \texttt{chapterbib} and \thestyle\ packages are loaded
+is unimportant.
+
+The \texttt{chapterbib} package provides an option \texttt{sectionbib}
+that puts the bibliography in a |\section*| instead of |\chapter*|,
+something that makes sense if there is a bibliography in each chapter.
+This option will not work when \thestyle\ is also loaded; instead, add
+the option to \thestyle.
+% (The \texttt{sectionbib} option can always be
+% given, but it only has meaning for the \texttt{book} and \texttt{report}
+% classes, or for classes derived from them.)
+
+Every |\include|d file must contain its own
+|\bibliography| command where the bibliography is to appear. The database
+files listed as arguments to this command can be different in each file,
+of course. However, what is not so obvious, is that each file must also
+contain a |\bibliographystyle| command, \emph{preferably with the same
+style argument}.
+% If different bibliography styles are specified for
+% different files, then the preprogrammed citation style (punctuation and
+% citation mode) will be that of the first bibliography style given. The
+% preprogrammed citation styles can only be changed in the preamble (see
+% Section~\ref{sec:priority}), something that guarantees a uniform style
+% for the entire document.\relax
+% \footnote{It would be relatively easy to allow changes in style anywhere
+% in the document, but this strikes me as bad policy. However, it is
+% provided for with the \texttt{docstrip} option \texttt{nopreonly}.}
+%
+% \iffalse
+%</notes>
+% \fi
+%
+% \subsection{Sorting and Compressing Numerical Citations}
+% \label{sec:sort}
+%
+% Another package by Donald Arseneau, \texttt{cite.sty}, reimplements the
+% entire (numerical) citation system such that one can control the
+% punctuation and citation format, all of which is done by \thestyle\ as
+% well. However, it also can sort and compress numerical citations,
+% something that is required by some journals.
+%
+% What this means is that when multiple citations are given with a single
+% |\cite| command, the normal order of the numbers is in the sequence
+% given. This is usually a wild list of numbers, such as [4,2,8,3]. With
+% the \texttt{cite} package, this list becomes [2--4,8].
+%
+% It is impossible to make the \texttt{cite} and \thestyle\ packages
+% compatible, since both reimplement |\cite| from scratch. Instead, I have
+% taken over some of the coding from \texttt{cite.sty}, modifying it for
+% \thestyle{}. This coding is activated by including one of the options
+% \texttt{sort} or \texttt{sort\&compress} in the |\usepackage| command.
+%
+% For author--year citations, the option \texttt{sort} orders the citations in
+% a single |\citep| or |\citet| command into the sequence in which they appear
+% in the list of references. This is normally alphabetical first, year second.
+% This should avoid citations of the type: ``James et~al.\ (1994b,a)''. For
+% author--year mode, the \texttt{sort\&compress} option is identical to
+% \texttt{sort}.
+%
+% \iffalse
+%<*notes>
+\head{Sorting and compressing citations}
+Do not use the \texttt{cite} package with \thestyle; rather use one of the
+options \texttt{sort} or \texttt{sort\&compress}.
+
+These also work with author--year citations, making multiple citations appear
+in their order in the reference list.
+
+%</notes>
+% \fi
+%
+% \subsection{Long Author List on First Citation}\label{sec:long}
+%
+% A feature that has often been requested by otherwise happy users of
+% \thestyle\ is one that is found in the \texttt{harvard} package as
+% standard: with the first citation of any reference, the full author list is
+% printed, and afterwards only the abbreviated list. One can control this
+% with |\citet*| for the first citation, and |\citet| or |\citep| thereafter.
+% However, the automatic feature is very desired.
+%
+% This can be activated with the option
+% \texttt{longnamesfirst}.
+%
+% \iffalse
+%<*notes>
+\head{Long author list on first citation}
+Use option \texttt{longnamesfirst} to have first citation automatically give
+the full list of authors.
+
+Suppress this for certain citations with |\shortcites{|\emph{key-list}|}|,
+given before the first citation.
+
+%</notes>
+% \fi
+%
+% \DescribeMacro{\shortcites}
+% Some references have so many authors that you want to suppress the
+% automatic long list only for them. In this case, issue
+% \begin{quote}
+% |\shortcites|\marg{key-list}
+% \end{quote}
+% before the first citations, and those included in \emph{key-list} will have
+% a short list on their first citation.
+%
+% Full author lists can still be forced at any time with the starred
+% variants.
+%
+% \section{Numerical Citations with Author--Year Styles}\label{sec:6.0}
+%
+% It is possible to produce numerical citations with any author-year
+% \texttt{.bst} file, with minimal change to the text. The commands |\citet|
+% and |\citep| will produce sensible results in both modes, without any special
+% editing. Obviously, the opposite is not possible; a \texttt{.bst} file
+% intended for numerical citation can never produce author--year citations,
+% simply because the information is not transferred to the auxiliary file.
+%
+% \subsection{Selecting Numerical Mode}
+% By default, \thestyle{} is in author--year mode. This can be changed by
+% \begin{enumerate}
+% \item selecting a numerical bibliography style with predefined
+% citation style, defined either in the package or in the local
+% configuration file;
+%
+% \item giving options \texttt{numbers} or \texttt{super} to the
+% |\usepackage| command;
+%
+% \item issuing |\bibpunct| with the 4th mandatory argument set to \texttt{n}
+% or \texttt{s};
+%
+% \item issuing |\citestyle| with the name of a predefined numerical
+% bibliography style.
+% \end{enumerate}
+% The methods are listed in order of increasing priority.
+%
+% The \thestyle{} package will automatically switch to numerical mode if
+% any one of the |\bibitem| entries fails to conform to the possible
+% author--year formats. There is no way to override this, since such an
+% entry would cause trouble in the author--year mode.
+%
+% There are certain special `numerical' styles, like that of the standard
+% \texttt{alpha.bst}, which include a non-numerical label in place of the
+% number, in the form
+% \begin{quote} |\bibitem[ABC95]{able95}| \end{quote}
+% As far as \thestyle\ is concerned, this label does not conform to the
+% author--year possibilities and is therefore considered to be numerical.
+% The citation mode switches to numerical, and |\cite{able95}| prints
+% [ABC95].
+%
+% See however, the end of Section~\ref{sec:yearless} for another possibility.
+% The above result can be achieved with
+% \begin{quote} |\bibitem[ABC95()]{able95}| \end{quote}
+%
+% \section{Local Configuration}
+% For \LaTeXe, it is possible to add a local configuration file
+% \thestyle\texttt{.cfg}, which is read in, if it exists, at
+% the end of the package. It may thus contain coding to supecede that in
+% the package, although its main purpose is to allow the user to add his
+% own |\bibstyle@|\textit{bst} definitions to couple citation punctuation
+% with local bibliography styles.
+%
+% \iffalse
+%<*notes>
+\head{Local configuration}
+Any local recoding or definitions can be put in \thestyle\texttt{.cfg} which
+is read in after the main package file.
+
+%</notes>
+% \fi
+%
+% \section{Options with \LaTeXe}\label{sec:opts}
+% One of the new features of \LaTeXe{} is \emph{options} for the packages,
+% in the same way as main styles (now called \emph{classes}) can take
+% options. This package is now installed with
+% \begin{quote}
+% |\documentclass[..]{...}|\\
+% |\usepackage[|\emph{options}|]{|\thestyle|}|
+% \end{quote}
+% \iffalse
+%<*notes>
+\head{Options that can be added to \texttt{\char`\\ usepackage}}
+% \fi
+% The options available provide another means of specifying the
+% punctuation for citations:
+\begin{description}
+\item[\ttfamily round] (default) for round parentheses;
+\item[\ttfamily square] for square brackets;
+\item[\ttfamily curly] for curly braces;
+\item[\ttfamily angle] for angle brackets;
+\item[\ttfamily colon] (default) to separate multiple citations with
+ colons;
+\item[\ttfamily comma] to use commas as separaters;
+\item[\ttfamily authoryear] (default) for author--year citations;
+\item[\ttfamily numbers] for numerical citations;
+\item[\ttfamily super] for superscripted numerical citations, as in
+ \textsl{Nature};
+\item[\ttfamily sort] orders multiple citations into the sequence in
+ which they appear in the list of references;
+\item[\ttfamily sort\&compress] as \texttt{sort} but in addition multiple
+ numerical citations are compressed if possible (as 3--6, 15);
+\item[\ttfamily longnamesfirst] makes the first citation of any reference
+ the equivalent of the starred variant (full author list) and subsequent
+ citations normal (abbreviated list);
+\item[\ttfamily sectionbib] redefines |\thebibliography| to issue
+ |\section*| instead of |\chapter*|; valid only for classes with a
+ |\chapter| command; to be used with the \texttt{chapterbib} package;
+\item[\ttfamily nonamebreak] keeps all the authors' names in a citation on
+ one line; causes overfull hboxes but helps with some \texttt{hyperref}
+ problems.
+\end{description}
+% \iffalse
+%</notes>
+% \fi
+%
+% If any of the formatting options are selected, the predefined citation
+% styles in the commands |\bibstyle@|\textit{bst} will be no longer be
+% effective. If either |\bibpunct| or |\citestyle| is given in the preamble,
+% the above punctuation options will no longer hold.
+%
+% \section{As Module to Journal-Specific Styles}
+% Although \thestyle{} is meant to be an all-purpose bibliographic style
+% \emph{package}, it may also be incorporated as a module to other
+% packages for specific journals. In this case, many of the general features may
+% be left off. This is allowed for with \texttt{docstrip} options that not
+% only leave off certain codelines, but also include extra ones. So far,
+% options exist for
+% \begin{description}
+% \item[\ttfamily subpack] produces a basic version with author--year only,
+% fixed citation punctuation, no |\bibpunct| nor |\citestyle| nor
+% predefined styles;
+% \item[\ttfamily subpack,egs] for journals of the \textsl{European Geophysical
+% Society}, in particular \textsl{Nonlinear Processes in Geophysics};
+% \item[\ttfamily subpack,agu] for \textsl{American Geophysical Union} journals.
+% \end{description}
+% The \texttt{subpack} option must always be used with \texttt{package}.
+%
+% Previous options \texttt{jgr} and \texttt{grl} have become obsolete due
+% to revisions in these journals; they have been replaced by the more
+% general \texttt{agu} option.
+%
+% \section{Reference Sheet}
+%
+% A summarization of the main points on using \thestyle\ can be obtained by
+% \LaTeX{}ing the file \texttt{natnotes.tex}, which is extracted from the main
+% source file \thestyle\texttt{.dtx} with the \texttt{docstrip} option
+% \texttt{notes}. This is intended to act as a handy reference sheet.
+%
+% This file should be extracted automatically by the supplied installation file,
+% \thestyle\texttt{.ins}.
+%
+%^^A The following is a summary that goes into the .sty file
+%^^A It is not printed in the documentation, since the Reference Sheet exists
+% \iffalse
+%<*package&!subpack>
+ % This package reimplements the LaTeX \cite command to be used for various
+ % citation styles, both author-year and numerical. It accepts BibTeX
+ % output intended for many other packages, and therefore acts as a
+ % general, all-purpose citation-style interface.
+ %
+ % With standard numerical .bst files, only numerical citations are
+ % possible. With an author-year .bst file, both numerical and
+ % author-year citations are possible.
+ %
+ % If author-year citations are selected, \bibitem must have one of the
+ % following forms:
+ % \bibitem[Jones et al.(1990)]{key}...
+ % \bibitem[Jones et al.(1990)Jones, Baker, and Williams]{key}...
+%<*apalike|all>
+ % \bibitem[Jones et al., 1990]{key}...
+%</apalike|all>
+%<*newapa|chicago|all>
+ % \bibitem[\protect\citeauthoryear{Jones, Baker, and Williams}{Jones
+ % et al.}{1990}]{key}...
+ % \bibitem[\protect\citeauthoryear{Jones et al.}{1990}]{key}...
+%</newapa|chicago|all>
+%<*astron|all>
+ % \bibitem[\protect\astroncite{Jones et al.}{1990}]{key}...
+%</astron|all>
+%<*authordate|all>
+ % \bibitem[\protect\citename{Jones et al., }1990]{key}...
+%</authordate|all>
+%<*harvard|all>
+ % \harvarditem[Jones et al.]{Jones, Baker, and Williams}{1990}{key}...
+%</harvard|all>
+ %
+ % This is either to be made up manually, or to be generated by an
+ % appropriate .bst file with BibTeX.
+ % Author-year mode || Numerical mode
+ % Then, \citet{key} ==>> Jones et al. (1990) || Jones et al. [21]
+ % \citep{key} ==>> (Jones et al., 1990) || [21]
+ % Multiple citations as normal:
+ % \citep{key1,key2} ==>> (Jones et al., 1990; Smith, 1989) || [21,24]
+ % or (Jones et al., 1990, 1991) || [21,24]
+ % or (Jones et al., 1990a,b) || [21,24]
+ % \cite{key} is the equivalent of \citet{key} in author-year mode
+ % and of \citep{key} in numerical mode
+ % Full author lists may be forced with \citet* or \citep*, e.g.
+ % \citep*{key} ==>> (Jones, Baker, and Williams, 1990)
+ % Optional notes as:
+ % \citep[chap. 2]{key} ==>> (Jones et al., 1990, chap. 2)
+ % \citep[e.g.,][]{key} ==>> (e.g., Jones et al., 1990)
+ % \citep[see][pg. 34]{key}==>> (see Jones et al., 1990, pg. 34)
+ % (Note: in standard LaTeX, only one note is allowed, after the ref.
+ % Here, one note is like the standard, two make pre- and post-notes.)
+ % \citealt{key} ==>> Jones et al. 1990
+ % \citealt*{key} ==>> Jones, Baker, and Williams 1990
+ % \citealp{key} ==>> Jones et al., 1990
+ % \citealp*{key} ==>> Jones, Baker, and Williams, 1990
+ % Additional citation possibilities (both author-year and numerical modes)
+ % \citeauthor{key} ==>> Jones et al.
+ % \citeauthor*{key} ==>> Jones, Baker, and Williams
+ % \citeyear{key} ==>> 1990
+ % \citeyearpar{key} ==>> (1990)
+ % \citetext{priv. comm.} ==>> (priv. comm.)
+ % Note: full author lists depends on whether the bib style supports them;
+ % if not, the abbreviated list is printed even when full requested.
+ %
+ % For names like della Robbia at the start of a sentence, use
+ % \Citet{dRob98} ==>> Della Robbia (1998)
+ % \Citep{dRob98} ==>> (Della Robbia, 1998)
+ % \Citeauthor{dRob98} ==>> Della Robbia
+ %
+%<*!209>
+ %
+ % Citation aliasing is achieved with
+ % \defcitealias{key}{text}
+ % \citetalias{key} ==>> text
+ % \citepalias{key} ==>> (text)
+%</!209>
+ %
+ % Defining the citation style of a given bib style:
+%<!nopreonly> % Use \bibpunct (in the preamble only) with 6 mandatory arguments:
+%<nopreonly> % Use \bibpunct (anywhere in the text) with 6 mandatory arguments:
+ % 1. opening bracket for citation
+ % 2. closing bracket
+ % 3. citation separator (for multiple citations in one \cite)
+ % 4. the letter n for numerical styles, s for superscripts
+ % else anything for author-year
+ % 5. punctuation between authors and date
+ % 6. punctuation between years (or numbers) when common authors missing
+ % One optional argument is the character coming before post-notes. It
+ % appears in square braces before all other arguments. May be left off.
+ % Example (and default) \bibpunct[, ]{(}{)}{;}{a}{,}{,}
+ %
+ % To make this automatic for a given bib style, named newbib, say, make
+ % a local configuration file, natbib.cfg, with the definition
+ % \newcommand{\bibstyle@newbib}{\bibpunct...}
+ % Then the \bibliographystyle{newbib} will cause \bibstyle@newbib to
+ % be called on THE NEXT LATEX RUN (via the aux file).
+ %
+%<!nopreonly> % Such preprogrammed definitions may be invoked in the text (preamble only)
+%<nopreonly> % Such preprogrammed definitions may be invoked anywhere in the text
+ % by calling \citestyle{newbib}. This is only useful if the style specified
+ % differs from that in \bibliographystyle.
+ %
+%<*!209>
+ % With \citeindextrue and \citeindexfalse, one can control whether the
+ % \cite commands make an automatic entry of the citation in the .idx
+ % indexing file. For this, \makeindex must also be given in the preamble.
+ %
+ % LaTeX2e Options: (for selecting punctuation)
+ % round - round parentheses are used (default)
+ % square - square brackets are used [option]
+ % curly - curly braces are used {option}
+ % angle - angle brackets are used <option>
+ % colon - multiple citations separated by colon (default)
+ % comma - separated by comma
+ % authoryear - selects author-year citations (default)
+ % numbers- selects numerical citations
+ % super - numerical citations as superscripts
+ % sort - sorts multiple citations according to order in ref. list
+ % sort&compress - like sort, but also compresses numerical citations
+ % longnamesfirst - makes first citation full author list
+ % sectionbib - puts bibliography in a \section* instead of \chapter*
+ % Punctuation so selected dominates over any predefined ones.
+ % LaTeX2e options are called as, e.g.
+ % \usepackage[square,comma]{natbib}
+%</!209>
+ % LaTeX the source file natbib.dtx to obtain more details
+%<!209> % or the file natnotes.tex for a brief reference sheet.
+ %-----------------------------------------------------------
+%</package&!subpack>
+% \fi
+%
+% \section{Options with \texttt{docstrip}}
+% The source \texttt{.dtx} file is meant to be processed with
+% \texttt{docstrip}, for which a number of options are available:
+% \begin{description}
+% \item[\ttfamily all] includes all of the other interfaces;
+%
+% \item[\ttfamily apalike] allows interpretation of minimal \texttt{apalike}
+% form of |\bibitem|;
+%
+% \item[\ttfamily newapa] allows |\citeauthoryear| to be in the optional
+% argument of |\bibitem| along with the punctuation commands of
+% \texttt{newapa.sty};
+%
+% \item[\ttfamily chicago] is the same as \texttt{newapa};
+%
+% \item[\ttfamily harvard] includes interpretation of |\harvarditem|;
+%
+% \item[\ttfamily astron] allows |\astroncite| to appear in the optional
+% argument of |\bibitem|;
+%
+% \item[\ttfamily authordate] adds the syntax of the |\citename| command.
+%
+% \end{description}
+%
+% This package file is intended to act as a module for other class files
+% written for specific journals, in which case the flexible
+% |\bibstyle@|{\em bst\/} commands are not wanted. Punctuation and
+% other style features are to be rigidly fixed. These journal options are
+% \begin{description}
+% \item[\ttfamily agu] for journals of the \textsl{American Geophysical
+% Union};
+%
+% \item[\ttfamily egs] for journals of the \textsl{European Geophysical
+% Society}, in particular \textsl{Nonlinear Processes in Geophysics}.
+%
+% \end{description}
+%
+% The remaining options are:
+% \begin{description}
+% \item[\ttfamily package] to produce a \texttt{.sty} package file with most
+% comments removed;
+%
+% \item[\ttfamily 209] (together with \texttt{package}) for a style option
+% file that will run under the older \LaTeX~2.09;
+%
+% \item[\ttfamily subpack] (together with \texttt{package}) for coding that
+% is to be included inside a larger package; even more comments are
+% removed, as well as \LaTeXe{} option handling and identification;
+% produces a basic \thestyle\ package for author--year only, fixed
+% citation style (punctuation);
+%
+% \item[\ttfamily notes] extracts a summary of usage to be used as a
+% reference sheet; the resulting file is to be \LaTeX{}ed;
+%
+% \item[\ttfamily nopreonly] allows |\citestyle| and |\bibpunct| to be
+% called anywhere in the text; this is considered possibly useful
+% with the \texttt{chapterbib} package where different chapters might
+% have different bibliography and citation styles; is only provided
+% in case I change my mind about this feature, but for now I
+% refuse to implement it;
+%
+% \item[\ttfamily driver] to produce a driver \texttt{.drv} file that will
+% print out the documentation under \LaTeXe. The documentation cannot
+% be printed under \LaTeX~2.09.
+%
+% \end{description}
+% The source file \texttt{\filename.dtx} is itself a driver file and can
+% be processed directly by \LaTeXe.
+%
+% \iffalse
+%<notes>\end{document}
+% \fi
+%
+% \StopEventually{\PrintIndex\PrintChanges}
+%
+% \section{The Coding}
+% This section presents and explains the actual coding of the macros.
+% It is nested between |%<*package>| and |%</package>|, which
+% are indicators to \texttt{docstrip} that this coding belongs to the package
+% file.
+%
+% The \texttt{docstrip} option |<subpack>| should only be called if the
+% coding is to be included as part of another package, in which case the
+% announcement text and \LaTeXe{} options are suppressed.
+%
+% An alternative version of this coding is provided for running as a
+% style file under \LaTeX~2.09. Code lines belonging to this are
+% indicated with guard |<209>|; those for LaTeXe{} only with |<!209>|.
+%
+% With \LaTeX\ release from \texttt{1995/12/01}, |\cite| is made robust,
+% something that I have adopted as well.
+%
+% Another change in the above release is that
+% |\G@refundefinedtrue|\footnote{In fact, it was only proposed to be
+% removed, but because several packages, including this one, were
+% adversely affected, the name was retained for the new coding.}
+% and the |\if@openbib| flag have been removed.
+% New, more effective, and compact, coding has replaced them. Rather than
+% relying on the kernel coding, I make \thestyle\ more
+% self-reliant.
+%
+% \subsection{Test for Specific Journals}
+% This package should not be loaded with the specific journal packages that
+% already include it; it is superfluous and can lead to contradictions.
+% \begin{macrocode}
+%<*package>
+%<*!209&!subpack>
+\@ifclassloaded{aguplus}{\PackageError{natbib}
+ {The aguplus class already includes natbib coding,\MessageBreak
+ so you should not add it explicitly}
+ {Type <Return> for now, but then later remove\MessageBreak
+ the command \protect\usepackage{natbib} from the document}
+ \endinput}{}
+\@ifclassloaded{nlinproc}{\PackageError{natbib}
+ {The nlinproc class already includes natbib coding,\MessageBreak
+ so you should not add it explicitly}
+ {Type <Return> for now, but then later remove\MessageBreak
+ the command \protect\usepackage{natbib} from the document}
+ \endinput}{}
+\@ifclassloaded{egs}{\PackageError{natbib}
+ {The egs class already includes natbib coding,\MessageBreak
+ so you should not add it explicitly}
+ {Type <Return> for now, but then later remove\MessageBreak
+ the command \protect\usepackage{natbib} from the document}
+ \endinput}{}
+%</!209&!subpack>
+% \end{macrocode}
+%
+% \subsection{Selecting Citation Punctuation and Other Modifications}
+% \begin{macro}{\bibstyle@xxx}
+% \changes{5.3}{1994 Sep 13}{Add \texttt{agsm} and \texttt{dcu} punctuation
+% styles from \texttt{harvard} series}
+% We begin by defining a number of punctuation styles for specific
+% author--year \texttt{.bst} files that I use.
+% They are placed here, near the beginning, so that another
+% user can easily find them to add his own. Some comments remain in the
+% stripped version too.
+% \begin{macrocode}
+%<*!subpack>
+ % Define citation punctuation for some author-year styles
+ % One may add and delete at this point
+%<!209> % Or put additions into local configuration file natbib.cfg
+\newcommand\bibstyle@chicago{\bibpunct{(}{)}{;}{a}{,}{,}}
+\newcommand\bibstyle@named{\bibpunct{[}{]}{;}{a}{,}{,}}
+\newcommand\bibstyle@agu{\bibpunct{[}{]}{;}{a}{,}{,~}}%Amer. Geophys. Union
+\newcommand\bibstyle@egs{\bibpunct{(}{)}{;}{a}{,}{,}}%Eur. Geophys. Soc.
+%<*all|harvard>
+\newcommand\bibstyle@agsm{\bibpunct{(}{)}{,}{a}{}{,}\gdef\harvardand{\&}}
+\newcommand\bibstyle@kluwer{\bibpunct{(}{)}{,}{a}{}{,}\gdef\harvardand{\&}}
+\newcommand\bibstyle@dcu{\bibpunct{(}{)}{;}{a}{;}{,}\gdef\harvardand{and}}
+%</all|harvard>
+% \end{macrocode}
+%
+% Here give the explicit punctuation for the specific journals; their
+% coding need not contain the punctuation macros |\bibpunct| and
+% |\bibstyle@xxx| since the punctuation is fixed for them.
+%
+% Activate citation sorting for the journals.
+% \changes{6.8b}{1998 July 2}{Turn off sorting for AGU and EGS}
+% \begin{macrocode}
+\newcommand\bibstyle@aa{\bibpunct{(}{)}{;}{a}{}{,}} %Astronomy & Astrophysics
+\newcommand\bibstyle@pass{\bibpunct{(}{)}{;}{a}{,}{,}}%Planet. & Space Sci
+\newcommand\bibstyle@anngeo{\bibpunct{(}{)}{;}{a}{,}{,}}%Annales Geophysicae
+\newcommand\bibstyle@nlinproc{\bibpunct{(}{)}{;}{a}{,}{,}}%Nonlin.Proc.Geophys.
+%</!subpack>
+%<agu>\newcommand\NAT@open{[} \newcommand\NAT@close{]}
+%<agu>\newcommand\NAT@sep{;} \newcommand\NAT@cmt{, }
+%<agu>\newcommand\NAT@aysep{,} \newcommand\NAT@yrsep{,~}
+%<agu|egs>\def\NAT@sort{0}
+%<egs>\newcommand\NAT@open{(} \newcommand\NAT@close{)}
+%<egs>\newcommand\NAT@sep{;} \newcommand\NAT@cmt{, }
+%<egs>\newcommand\NAT@aysep{,} \newcommand\NAT@yrsep{,}
+% \end{macrocode}
+%
+% \changes{6.5}{1997 Jan 30}{Fix \texttt{esa} style for new note system}
+% \changes{7.0}{1999 May 7}{Fix \texttt{esa} style again}
+% Next, the same thing is done for some numerical styles. A major
+% difference here is that the |\@biblabel| and |\@cite| commands must also
+% be redefined in many cases. These redefinitions must be made with the
+% |\gdef| (global definition) command.
+% \begin{macrocode}
+%<*!subpack>
+ % Define citation punctuation for some numerical styles
+\newcommand\bibstyle@cospar{\bibpunct{/}{/}{,}{n}{}{}%
+ \gdef\NAT@biblabelnum##1{##1.}}
+\newcommand\bibstyle@esa{\bibpunct{(Ref.~}{)}{,}{n}{}{}%
+ \gdef\NAT@biblabelnum##1{##1.\hspace{1em}}}
+\newcommand\bibstyle@nature{\bibpunct{}{}{,}{s}{}{\textsuperscript{,}}%
+ \gdef\NAT@biblabelnum##1{##1.}}
+% \end{macrocode}
+%
+% Finally, the standard \LaTeX{} (numerical) citation styles are included
+% along with their \thestyle\ modifications (author--year).
+% \begin{macrocode}
+ % The standard LaTeX styles
+\newcommand\bibstyle@plain{\bibpunct{[}{]}{,}{n}{}{,}}
+\let\bibstyle@alpha=\bibstyle@plain
+\let\bibstyle@abbrv=\bibstyle@plain
+\let\bibstyle@unsrt=\bibstyle@plain
+ % The author-year modifications of the standard styles
+\newcommand\bibstyle@plainnat{\bibpunct{[}{]}{,}{a}{,}{,}}
+\let\bibstyle@abbrvnat=\bibstyle@plainnat
+\let\bibstyle@unsrtnat=\bibstyle@plainnat
+% \end{macrocode}
+% \end{macro}
+%
+% \subsection{\LaTeXe{} Options}
+% \begin{macro}{\ifNAT@numbers}
+% \changes{5.5}{1995 Mar 21}{Add flag for switching between cite styles}
+% \begin{macro}{\ifNAT@super}
+% \changes{5.5}{1995 Mar 21}{Add flag for switching between cite styles}
+% Two flags are used to keep track of the citation style. The flag
+% |\ifNAT@numbers| is \meta{false} by default (author--year) and switches
+% to \meta{true} for numerical citations. The flag |\ifNAT@super| indicates
+% if the numerical citation is to be done with superscripts.
+% \begin{macrocode}
+\newif\ifNAT@numbers \NAT@numbersfalse
+\newif\ifNAT@super \NAT@superfalse
+%</!subpack>
+% \end{macrocode}
+% \end{macro}\end{macro}
+%
+% \begin{macro}{\DeclareOption}
+% \changes{5.0}{1994 May 18}{Add \LaTeXe{} options.}
+% \changes{5.3}{1994 Sep 13}{Add options \texttt{angle} and \texttt{curly}}
+% \changes{6.0}{1995 Sep 6}{Add option \texttt{bibstyle}}
+% \changes{6.0}{1995 Sep 6}{Execute \texttt{nobibstyle} with all options}
+% \changes{6.1}{1995 Nov 27}{Add option \texttt{openbib}}
+% \changes{6.4}{1996 Sep 1}{Add option \texttt{sectionbib}}
+% \changes{6.4}{1996 Sep 13}{Add option \texttt{sort}}
+% \changes{6.7}{1997 Jul 14}{Add option \texttt{longnamesfirst}}
+% \changes{6.8c}{1998 Jul 14}{Add option \texttt{nonamebreak}}
+% For \LaTeXe, we can define some options to be used with the |\usepackage|
+% command that loads the \thestyle{} package. These are an additional means
+% of specifying the citation punctuation and scheme.
+%
+% The standard option \texttt{openbib} is also defined here so that its
+% behaviour is entirely under my control. Relying on the standard classes
+% can lead to trouble.
+% \begin{macrocode}
+%<*!subpack&!209>
+\DeclareOption{numbers}{\NAT@numberstrue
+ \ExecuteOptions{square,comma,nobibstyle}}
+\DeclareOption{super}{\NAT@supertrue\NAT@numberstrue
+ \renewcommand\NAT@open{}\renewcommand\NAT@close{}
+ \ExecuteOptions{nobibstyle}}
+\DeclareOption{authoryear}{\NAT@numbersfalse
+ \ExecuteOptions{round,colon,bibstyle}}
+\DeclareOption{round}{%
+ \renewcommand\NAT@open{(} \renewcommand\NAT@close{)}
+ \ExecuteOptions{nobibstyle}}
+\DeclareOption{square}{%
+ \renewcommand\NAT@open{[} \renewcommand\NAT@close{]}
+ \ExecuteOptions{nobibstyle}}
+\DeclareOption{angle}{%
+ \renewcommand\NAT@open{$<$} \renewcommand\NAT@close{$>$}
+ \ExecuteOptions{nobibstyle}}
+\DeclareOption{curly}{%
+ \renewcommand\NAT@open{\{} \renewcommand\NAT@close{\}}
+ \ExecuteOptions{nobibstyle}}
+\DeclareOption{comma}{\renewcommand\NAT@sep{,}
+ \ExecuteOptions{nobibstyle}}
+\DeclareOption{colon}{\renewcommand\NAT@sep{;}
+ \ExecuteOptions{nobibstyle}}
+\DeclareOption{nobibstyle}{\let\bibstyle=\@gobble}
+\DeclareOption{bibstyle}{\let\bibstyle=\@citestyle}
+\newif\ifNAT@openbib \NAT@openbibfalse
+\DeclareOption{openbib}{\NAT@openbibtrue}
+\DeclareOption{sectionbib}{\def\NAT@sectionbib{on}}
+\def\NAT@sort{0}
+\DeclareOption{sort}{\def\NAT@sort{1}}
+\DeclareOption{sort&compress}{\def\NAT@sort{2}}
+\@ifpackageloaded{cite}{\PackageWarningNoLine{natbib}
+ {The `cite' package should not be used\MessageBreak
+ with natbib. Use option `sort' instead}\ExecuteOptions{sort}}{}
+\newif\ifNAT@longnames\NAT@longnamesfalse
+\DeclareOption{longnamesfirst}{\NAT@longnamestrue}
+\DeclareOption{nonamebreak}{\def\NAT@nmfmt#1{\mbox{\NAT@up#1}}}
+%</!subpack&!209>
+\def\NAT@nmfmt#1{{\NAT@up#1}}
+% \end{macrocode}
+% Before version~6.0, the punctuation options had the lowest priority,
+% being overridden by any |\bibstyle@|\textit{bst} command. It was necessary
+% to add the option \texttt{nobibstyle} to make them effective. Now this
+% option is automatically executed whenever a punctuation option is chosen.
+% The reason is that \texttt{nobibstyle} is either superfluous (no
+% predefined citation style is present) or always necessary to make the
+% other options meaningful.
+%
+% It seems to be better practice to make any explicit choices to have
+% higher priority over implicit ones.
+%
+% The option \texttt{bibstyle} reactivates the predefined commands, just in
+% case this is needed, as it is for the option \texttt{authoryear}. This
+% leaves the predefined styles functioning, since it does not really
+% determine the citation style, but rather establishes a default which may
+% be overwritten by a prestored one. For this reason, this option must be
+% defined very early so that any explicit punctuation options overwrite the
+% defaults. (Options are executed in the order defined.)
+%
+% \end{macro}
+%
+% \subsection{Selecting Citation Punctuation and Other Modifications}
+% \begin{macro}{\bibstyle}
+% \changes{5.4}{1994 Nov 24}{Move \cs{ProcessOptions} to after definition
+% of \cs{bibstyle}}
+% The pre-defined punctuation styles are associated with particular
+% \texttt{.bst} files. This is implemented by means of the standard
+% |\bibliographystyle| command that specifies the name of the \texttt{.bst}
+% file that is to be used by \btx. Some \LaTeX{} manuals erroneously state
+% that this command must be issued prior to any |\cite| commands. If that
+% were the case, the task of invoking the style definitions would be much
+% easier, for they certainly must be issued before the first |\cite|.
+% However, I have always called |\bibliographystyle| together with
+% |\bibliography|, well after all |\cite| commands.
+%
+% In fact, all that |\bibliographystyle|\marg{bst} does is to write
+% |\bibstyle|\marg{bst} to the auxiliary file. This file, and all its
+% contents, will be read in at the beginning of the next \LaTeX{} run; to
+% be precise, it is read in by |\begin{document}|. The command |\bibstyle| is
+% then executed at that point on the next run. However, it is
+% defined to do nothing more than to swallow up its argument! In other
+% words, the combination |\bibliographystyle| and |\bibstyle| do absolutely
+% nothing to the \LaTeX{} runs. In fact, |\bibstyle| is a command for
+% \btx{} alone.
+%
+% I have taken advantage of this to redefine |\bibstyle| to execute the
+% \texttt{bst}-specific definitions. This definition is made here before
+% |\ExecuteOptions| so that options may make use of it; the option
+% \texttt{nobibstyle} turns it off, for example.
+% \begin{macrocode}
+%<*!subpack>
+\renewcommand\bibstyle[1]{\@ifundefined{bibstyle@#1}{\relax}
+ {\csname bibstyle@#1\endcsname}}
+% \end{macrocode}
+% This is executed only when the auxiliary file is read in, and that is
+% when |\begin{document}| is issued. Thus this is well before any |\cite|
+% commands. It is for this reason that any definitions in the
+% |\bibstyle@xxx| commands must be global.
+%
+% A minor problem arises in that the auxiliary file is read in a second
+% time, at the end of the run, to check whether any labels have changed.
+% Sometimes, re-executing the |\bibstyle@xxx| command at this point
+% produces error messages. To avoid this, |\bibstyle| is reset to its
+% normal, do-nothing, definition after |\begin{document}|.
+%
+% \LaTeXe{} provides a better way of adding commands to |\document|,
+% which is then exploited here. Paradoxically, the problem with re-reading
+% the auxiliary file does not seem to arise for this version.
+%
+% (|\NAT@set@cites| must also be executed at the start of the document; for
+% \LaTeXe, this is added later when the macro is defined.)
+% \begin{macrocode}
+%<*209>
+\let\ori@document=\document
+\renewcommand\document{\ori@document\global\let\bibstyle=\@gobble
+ \NAT@set@cites}
+%</209>
+%<!209>\AtBeginDocument{\global\let\bibstyle=\@gobble}
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\citestyle}
+% \changes{5.4}{1995 Feb 03}{Add macro}
+% \changes{5.5}{1995 Mar 24}{Make preamble only}
+% To allow one to invoke preprogrammed punctuation styles that are
+% different from the name of the bibliography style specified by
+% |\bibliographystyle|, call |\citestyle| in the preamble. This then
+% deactivates |\bibstyle| so that any preprogrammed punctuations become
+% ineffective.
+%
+% This, and all other punctuation (citation style) declarations, may only
+% be used in the preamble, as of version 5.5. (Previously they could only
+% be used after the preamble, but the preamble is more logical.)
+% \begin{macrocode}
+\let\@citestyle\bibstyle
+\newcommand\citestyle[1]{\@citestyle{#1}\let\bibstyle\@gobble}
+%<!209&!nopreonly>\@onlypreamble{\citestyle}\@onlypreamble{\@citestyle}
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\bibpunct}
+% \changes{5.4}{1994 Nov 24}{Add superscript style of citations}
+% \changes{5.5}{1995 Mar 21}{Use flags to select citation style}
+% \changes{5.5}{1995 Mar 24}{Make preamble only}
+% \changes{6.0}{1995 Sep 6}{Sets \cs{bibstyle} to \cs{@gobble}}
+% \changes{6.0}{1995 Sep 6}{Declare \cs{NAT@numbersfalse} before testing 4th
+% argument}
+% \changes{6.0}{1995 Sep 19}{Add optional argument for \cs{NAT@cmt}}
+% \changes{7.0}{1999 May 7}{Add blank to default of first argument}
+% Now |\bibpunct| is defined. It sets various punctuation commands equal to
+% its arguments. It also switches to numerical style if that is specified
+% by the fourth argument. This is done by setting the citation style
+% flag |NAT@numbers| accordingly. The internal cite macros are later
+% set to the style-dependent definitions by calling |\NAT@set@cites|.
+%
+% The fourth argument can also be \texttt{s} for superscript, which
+% sets both the numerical and the |\NAT@super| flags.
+%
+% An optional argument has been added to determine the punctuation that
+% precedes a trailing note. This makes the counting of mandatory arguments
+% somewhat confused, since the fourth argument is now |#5|.
+%
+% \begin{macrocode}
+%<!209>\newcommand\bibpunct[7][, ]%
+%<209>\newcommand\bibpunct{\@ifnextchar[{\@bibpunct}{\@bibpunct[, ]}}
+%<209>\def\@bibpunct[#1]#2#3#4#5#6#7%
+ {\gdef\NAT@open{#2}\gdef\NAT@close{#3}\gdef
+ \NAT@sep{#4}\global\NAT@numbersfalse\ifx #5n\global\NAT@numberstrue
+ \else
+ \ifx #5s\global\NAT@numberstrue\global\NAT@supertrue
+ \fi\fi
+ \gdef\NAT@aysep{#6}\gdef\NAT@yrsep{#7}%
+ \gdef\NAT@cmt{#1}%
+ \global\let\bibstyle\@gobble
+%<nopreonly> \NAT@set@cites
+ }
+%<*!nopreonly>
+%<!209>\@onlypreamble{\bibpunct}
+%<209>\def\do{\noexpand\do\noexpand}
+%<209>\edef\@preamblecmds{\@preamblecmds \do\bibpunct \do\citestyle}
+%</!nopreonly>
+%</!subpack>
+% \end{macrocode}
+% The command turns off |\bibstyle| so that the predefined
+% |\bibstyle@|\textit{bst} commands no longer work. Thus |\bibpunct| has
+% priority over the predefined styles.
+% \end{macro}
+%
+% \subsection{Setting the Defaults}
+% For \LaTeXe, the defaults (punctuation and scheme type) are set with the
+% |\ExecuteOptions| command. For \LaTeX~2.09, the default scheme is
+% author--year, and punctuation can only be set with |\bibpunct|.
+%
+% \begin{macro}{\NAT@open}
+% \changes{5.5}{1995 May 14}{Renamed from \cs{@citebegin}}
+% \begin{macro}{\NAT@close}
+% \changes{5.5}{1995 May 14}{Renamed from \cs{@citeend}}
+% \begin{macro}{\NAT@sep}
+% \changes{5.5}{1995 May 14}{Renamed from \cs{@citesep}}
+% \begin{macro}{\NAT@aysep}
+% \changes{5.5}{1995 May 14}{Renamed from \cs{@auyrsep}}
+% \begin{macro}{\NAT@yrsep}
+% \changes{5.5}{1995 May 14}{Renamed from \cs{@yrsep}}
+% \begin{macro}{\NAT@cmt}
+% \changes{6.0}{1995 Sep 19}{Add macro}
+% \changes{6.9}{1999 Feb 25}{Remove hardwired spaces after \cs{NAT@cmt},
+% adding them to default definition instead}
+% The five punctuation characters for citations are the start and stop
+% brackets, the character between multiple citations, the character between
+% the authors and year (parenthetical only), and the character between
+% adjacent years when the common author list is omitted.
+% A sixth one has been added: the character preceding post-notes,
+% including any possible space.
+% Define their default values.
+% \begin{macrocode}
+%<!agu&!egs>\newcommand\NAT@open{(} \newcommand\NAT@close{)}
+%<!agu&!egs>\newcommand\NAT@sep{;}
+% \end{macrocode}
+% \end{macro}\end{macro}\end{macro}\end{macro}\end{macro}\end{macro}
+% \changes{6.0}{1995 Sep 19}{Remove \cs{ExecuteOptions} since default
+% style determined by definitions}
+% The option \texttt{authoryear} was originally provided to serve as the
+% default; hence its definition includes \texttt{bibstyle}. However, this
+% is not necessary since all the appropriate parameters are set to these
+% values anyway. (One could consider removing \texttt{bibstyle}.)
+% \begin{macrocode}
+%<*!subpack&!209>
+%\ExecuteOptions{authoryear}
+\ProcessOptions
+%</!subpack&!209>
+%<!agu&!egs>\newcommand\NAT@aysep{,} \newcommand\NAT@yrsep{,}
+%<!agu&!egs>\newcommand\NAT@cmt{, }
+% \end{macrocode}
+%
+% \subsection{Internal Citing Macros}
+% A number of internal macros (|\@citex|, |\@cite|, |\@biblabel|, and
+% |\@bibsetup|) need to have different definitions for author--year and
+% numerical schemes. They are defined here for the two different styles,
+% with different names, and which ones become active depend on the citation
+% style flags |\ifNAT@numbers| and |\ifNAT@super|.
+%
+% The coding for the journals always defines the internal macros directly
+% as the author--year version, since they can never do any switching.
+%
+% \begin{macro}{\@cite}
+% \changes{5.5}{1995 Mar 21}{Is \cs{let} equal to the numerical or
+% author--year definition}
+% \begin{macro}{\NAT@cite}
+% \changes{4.2}{1993 Dec 2}{Reversed optional text no longer needs to include
+% a trailing blank}
+% \changes{5.0}{1994 May 18}{Add optional notes after as well as before
+% citation.}
+% \changes{5.5}{1995 Mar 13}{Add command space in place of space}
+% \changes{5.5}{1995 Mar 13}{Use \cs{if}\cs{relax}\texttt{\#2}\cs{relax}
+% in place of \cs{if}\texttt{\#2}\cs{@empty}}
+% \changes{5.5}{1995 Mar 21}{Renamed from \cs{@cite}}
+% \changes{6.6}{1997 May 26}{Use flag \cs{ifNAT@par} to suppress braces
+% optionally}
+% \changes{6.8}{1998 Feb 19}{Add \cs{endgroup} to terminate group}
+% \changes{6.9a}{1999 Apr 20}{Change test for empty notes to asterix, not \cs{relax}}
+% \begin{macro}{\NAT@citenum}
+% \changes{5.0}{1994 May 18}{Add optional notes after as well as before
+% citation.}
+% \changes{5.5}{1995 Mar 13}{Add command space in place of space}
+% \changes{5.5}{1995 Mar 13}{Use \cs{if}\cs{relax}\texttt{\#2}\cs{relax}
+% in place of \cs{if}\texttt{\#2}\cs{@empty}}
+% \changes{5.5}{1995 Mar 21}{Renamed from \cs{@citenum}}
+% \changes{6.5}{1997 Jan 30}{Numericals always print notes if present, do not
+% test for any flag first}
+% \changes{6.6}{1997 May 27}{Can be textual or parenthetical}
+% \changes{6.8}{1998 Feb 19}{Add \cs{endgroup} to terminate group}
+% \changes{6.8}{1998 Feb 19}{Use \cs{NAT@@open} and \cs{NAT@@close} instead
+% of \cs{NAT@open} and \cs{NAT@close}}
+% \begin{macro}{\NAT@citesuper}
+% \changes{5.4}{1994 Nov 24}{Add macro for superscripts}
+% \changes{5.5}{1995 Mar 21}{Renamed from \cs{@citesuper}}
+% \changes{5.5}{1995 Mar 27}{Prints post-note only if present}
+% \changes{6.2}{1995 Feb 2}{Get superscript font size right; use
+% \cs{textsuperscript}}
+% \changes{6.6}{1997 Jun 4}{Modify for new \cs{NAT@citexnum}}
+% \changes{6.8}{1998 Feb 19}{Add \cs{endgroup} to terminate group}
+% \changes{7.0}{1999 May 7}{Add \cs{citenumfont} for numbers}
+% Define the internal |\@cite| commands that prints the assembled string of
+% citation label texts, plus possible optional notes, before and after. The
+% numerical version (now) the same, where previously (before 6.8) it used
+% |\NAT@open| and |\NAT@close| so that braces were always present. (Keep the
+% separate definitions anyway in case a difference should arise later.) In both
+% cases, the notes are included (if present) only for parenthetical citations
+% (|\ifNAT@swa| is \meta{true}) while for textual citations, they are printed
+% by |\@citex|. The flag |\ifNAT@par| suppresses parentheses if \meta{false},
+% which is used with |\citealt|, |\citealp|, |\citeyear|, and |\citeauthor|
+% (both numerical and author--year modes).
+%
+% The superscript citation prints only the following, not the preceding,
+% note, and then only if it is present.
+%
+% Use the construction |\if*#2*| to test for empty note argument. Previously
+% used |\relax| in place of |*| but then it turned out that if the text began
+% with a robust command (like |\S|) the |\protect| command implicit here is
+% equal to |\relax| so the condition is \meta{true}. Now any notes beginning
+% with an asterix will give trouble.
+%
+% \begin{macrocode}
+%<subpack>\renewcommand\@cite%
+%<!subpack>\newcommand\NAT@cite%
+ [3]{\ifNAT@swa\NAT@@open\if*#2*\else#2\ \fi
+ #1\if*#3*\else\NAT@cmt#3\fi\NAT@@close\else#1\fi\endgroup}
+%<*!subpack>
+\newcommand\NAT@citenum%
+ [3]{\ifNAT@swa\NAT@@open\if*#2*\else#2\ \fi
+ #1\if*#3*\else\NAT@cmt#3\fi\NAT@@close\else#1\fi\endgroup}
+\newcommand\NAT@citesuper[3]{\ifNAT@swa
+\unskip\hspace{1\p@}\textsuperscript{#1}%
+ \if*#3*\else\ (#3)\fi\else #1\fi\endgroup}
+%<!209>\providecommand
+%<209>\@ifundefined{textsuperscript}{\newcommand
+ \textsuperscript[1]{\mbox{$^{\mbox{\scriptsize#1}}$}}
+%<209>}{}
+%</!subpack>
+% \end{macrocode}
+% \end{macro}\end{macro}\end{macro}\end{macro}
+%
+% \begin{macro}{\@citex}
+% \changes{5.5}{1995 Mar 21}{Is \cs{let} equal to the numerical or
+% author--year definition}
+% \changes{6.1}{1995 Nov 22}{Use \cs{NAT@citeundefined}}
+% \changes{6.6}{1997 May 17}{Add \cs{NAT@ctype} for author, year, or both}
+% \begin{macro}{\NAT@citexnum}
+% \changes{5.4}{1994 Nov 24}{Make like \LaTeXe{} definition instead of 2.09}
+% \changes{5.5}{1995 Mar 21}{Renamed from \cs{@citexnum}}
+% \changes{6.0}{1995 Sep 4}{Prints \cs{NAT@num} instead of \cs{b@citeb}}
+% \changes{6.4}{1996 Sep 12}{Add \cs{NAT@space} for variable spacing between
+% numericals and superscripts}
+% \changes{6.4}{1996 Oct 2}{Add dummy macros for \texttt{hyperref.sty}}
+% \changes{6.6}{1997 May 17}{Add \cs{NAT@ctype} for author, year, or number;
+% can be textual or parethetical}
+% \changes{6.6}{1997 Jun 3}{Re-write for sorting and compression}
+% \changes{6.6}{1997 Jun 25}{Improve \texttt{hyperref} support}
+% \changes{6.7}{1997 Jul 14}{Suppress repeated authors with numerical
+% \cs{citet}}
+% \changes{6.7}{1997 Jul 16}{Add \cs{ifNAT@longnames} test}
+% The original definition of |\@citex| is used as basis for |\NAT@citexnum|,
+% the version for numerical citations. What it does is to write a
+% |\citation| command to the auxiliary file (for \btx), and then parses the
+% second argument, the list of citation keys. These keys have to be decoded
+% into the actual label text contained in |\b@|\emph{key} (a number or
+% author--year), and put together as the argument of |\@cite|.
+% For a textual citation (|\ifNAT@swa| \meta{false}), the authors are printed
+% and then the number in parentheses. For multiple citations (silly thing) each
+% number is in separate parentheses preceded by authors.
+%
+% The temporary command |\@citeb| takes on the value of each of the keys in
+% turn; |\@citea| is the separator between multiple citations, initially
+% set to nothing, becoming |\NAT@sep| plus line-break suppression
+% afterwards. The |\@firstofone| macro removes any leading blanks in
+% |\@citeb|, making |\cite{key1, key2}| possible. If |\b@|\emph{key} is
+% not defined (as on the first run, for example), a warning is printed, and
+% a question mark inserted. Finally, the decoded label text is placed into
+% an |\hbox| to prevent it from being split.
+%
+% As of version 6.0, the numerical label text is to be found in |\NAT@num|,
+% whereas previously it was the entire label, |\b@|\emph{key}.
+%
+% Note that here, and in later coding, internal names beginning with
+% |\@cite..| are employed; these names are used in the original \LaTeX{}
+% coding for the same functions. Therefore, if there are other packages
+% that have name conflicts with \thestyle, they will also have conflicts with
+% standard \LaTeX\ too.
+%
+% The number |\NAT@ctype| controls whether author (1), year (2), or number (0)
+% is output by this macro. A value of 4 produces the cite alias.
+%
+% For compatibility with the \texttt{chapterbib} package of Donald Arseneau,
+% add |\@extra@b@citeb| to the cite key; this contains the number of the
+% included file in order to distinguish the same citation in separate files
+% which then belong to different bibliography listings.
+%
+% The list of citation keys is in |#3|; this is sorted by |\NAT@sort@cites|
+% and returned in |\NAT@cite@list|. If sorting is turned off, this list is
+% the same as the input. If compression of numerical lists is active
+% (|NAT@sort|=2) only the parenthetical output is affected.
+% \begin{macrocode}
+%<209>\let\@firstofone\@iden
+%<!209>\providecommand\@firstofone[1]{#1}
+%<*!subpack>
+\newcommand\NAT@citexnum{}
+\def\NAT@citexnum[#1][#2]#3{%
+%<!209> \NAT@sort@cites{#3}%
+ \let\@citea\@empty
+ \@cite{\def\NAT@num{-1}\let\NAT@last@yr\relax\let\NAT@nm\@empty
+%<!209> \@for\@citeb:=\NAT@cite@list\do
+%<209> \@for\@citeb:=#3\do
+ {\edef\@citeb{\expandafter\@firstofone\@citeb}%
+ \if@filesw\immediate\write\@auxout{\string\citation{\@citeb}}\fi
+ \@ifundefined{b@\@citeb\@extra@b@citeb}{%
+%<209> {\reset@font\bf ?}\@warning
+%<!209> {\reset@font\bfseries?}
+%<!209> \NAT@citeundefined\PackageWarning{natbib}%
+ {Citation `\@citeb' on page \thepage \space undefined}}%
+ {\let\NAT@last@num\NAT@num\let\NAT@last@nm\NAT@nm
+ \NAT@parse{\@citeb}%
+%<*!subpack&!209>
+ \ifNAT@longnames\@ifundefined{bv@\@citeb\@extra@b@citeb}{%
+ \let\NAT@name=\NAT@all@names
+ \global\@namedef{bv@\@citeb\@extra@b@citeb}{}}{}%
+ \fi
+%</!subpack&!209>
+ \ifNAT@full\let\NAT@nm\NAT@all@names\else
+ \let\NAT@nm\NAT@name\fi
+% \end{macrocode}
+% For compression of numerical citations, we need to save the last number;
+% use |\NAT@last@num| for this purpose. Use |\NAT@last@nm| to save last
+% names to check for repetitions.
+%
+% For parenthetical (\LaTeX\ standard) produce only the number (exception:
+% year is allowed for |\citeyearpar|, but without sorting); any notes are
+% added in the |\@cite| macro. For textual, print the authors and then the
+% number in parentheses. This is done for each citation of a multiple set,
+% unlike the parenthetical version where all citations appear in a single pair
+% of parentheses.
+%
+% The hyperlink start and end are to bracket only the number; however, if
+% only the authors or only the year are printed, then these are bracketed.
+% Numbers are not compressed if \texttt{hyperref} is loaded, since every
+% reference must be present.
+% \begin{macrocode}
+ \ifNAT@swa
+ \ifnum\NAT@ctype>1\relax\@citea
+ \hyper@natlinkstart{\@citeb\@extra@b@citeb}%
+ \ifnum\NAT@ctype=2\relax\NAT@test{\NAT@ctype}%
+%<!209> \else\NAT@alias
+ \fi\hyper@natlinkend\else
+%<*!209>
+ \ifnum\NAT@sort>1
+ \begingroup\catcode`\_=8
+ \ifcat _\ifnum\z@<0\NAT@num _\else A\fi
+ \global\let\NAT@nm=\NAT@num \else \gdef\NAT@nm{-2}\fi
+ \ifcat _\ifnum\z@<0\NAT@last@num _\else A\fi
+ \global\@tempcnta=\NAT@last@num \global\advance\@tempcnta by\@ne
+ \else \global\@tempcnta\m@ne\fi
+ \endgroup
+ \ifnum\NAT@nm=\@tempcnta
+ \ifx\NAT@last@yr\relax
+ \edef\NAT@last@yr{\@citea \mbox{\noexpand\citenumfont\NAT@num}}%
+ \else
+ \edef\NAT@last@yr{--\penalty\@m\mbox{\noexpand\citenumfont\NAT@num}}%
+ \fi
+ \else
+ \NAT@last@yr \@citea \mbox{\citenumfont\NAT@num}%
+ \let\NAT@last@yr\relax
+ \fi
+ \else
+%</!209>
+ \@citea \mbox{\hyper@natlinkstart{\@citeb\@extra@b@citeb}%
+ {\citenumfont\NAT@num}\hyper@natlinkend}%
+%<!209> \fi
+ \fi
+ \def\@citea{\NAT@sep\penalty\@m\NAT@space}%
+% \end{macrocode}
+% For textual citations, test what the output is to be (number, year,
+% author) and also test for comments.
+% \begin{macrocode}
+ \else
+ \ifcase\NAT@ctype\relax
+ \ifx\NAT@last@nm\NAT@nm \NAT@yrsep\penalty\@m\NAT@space\else
+ \@citea \NAT@test{1}\ \NAT@@open
+ \if*#1*\else#1\ \fi\fi \NAT@mbox{%
+ \hyper@natlinkstart{\@citeb\@extra@b@citeb}%
+ {\citenumfont\NAT@num}\hyper@natlinkend}%
+ \def\@citea{\NAT@@close\NAT@sep\penalty\@m\ }%
+ \or\@citea
+ \hyper@natlinkstart{\@citeb\@extra@b@citeb}%
+ \NAT@test{\NAT@ctype}\hyper@natlinkend
+ \def\@citea{\NAT@sep\penalty\@m\ }%
+ \or\@citea
+ \hyper@natlinkstart{\@citeb\@extra@b@citeb}%
+ \NAT@test{\NAT@ctype}\hyper@natlinkend
+ \def\@citea{\NAT@sep\penalty\@m\ }%
+%<*!209>
+ \or\@citea
+ \hyper@natlinkstart{\@citeb\@extra@b@citeb}%
+ \NAT@alias\hyper@natlinkend
+ \def\@citea{\NAT@sep\penalty\@m\ }%
+%</!209>
+ \fi
+ \fi
+ }}%
+%<!209> \ifnum\NAT@sort>1\relax\NAT@last@yr\fi
+ \ifNAT@swa\else\ifnum\NAT@ctype=0\if*#2*\else
+ \NAT@cmt#2\fi \NAT@@close\fi\fi}{#1}{#2}}
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\NAT@test}
+% \changes{6.6}{1997 May 29}{Add macro}
+% For numerical mode, need to test if there really is a name or date; if a
+% numerical \texttt{.bst} file is being used, there will not be any names or
+% dates. This macro tests and writes |\NAT@nm| or |\NAT@date| according to
+% its argument being 1 or 2.
+% \begin{macrocode}
+\newcommand\NAT@test[1]{\ifnum#1=1 \ifx\NAT@nm\NAT@noname
+%<209> {\reset@font\bf(author?)}\@warning
+%<!209> {\reset@font\bfseries(author?)}\PackageWarning{natbib}
+ {Author undefined for citation`\@citeb'
+%<209> ^^J
+%<!209> \MessageBreak
+ on page \thepage}\else \NAT@nm \fi
+ \else \if\relax\NAT@date\relax
+%<209> {\reset@font\bf(author?)}\@warning
+%<!209> {\reset@font\bfseries(year?)}\PackageWarning{natbib}
+ {Year undefined for citation`\@citeb'
+%<209> ^^J
+%<!209> \MessageBreak
+ on page \thepage}\else \NAT@date \fi \fi}
+%</!subpack>
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\citenumfont}
+% \changes{7.0}{1999 May 7}{Add macro to format numerical citations}
+% To set the numerical citations in a different font, define |\citenumfont|.
+% \begin{macrocode}
+\let\citenumfont=\relax
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\NAT@citex}
+% \changes{5.2}{1994 Aug 25}{Make like \LaTeXe{} definition instead of 2.09}
+% \changes{5.4}{1994 Nov 24}{Change space to command space for text cites}
+% \changes{5.4}{1995 Feb 6}{Add test for adjacent citations having equal
+% authors and years}
+% \changes{5.5}{1995 Mar 21}{Renamed from \cs{@citex}}
+% \changes{6.0}{1995 Sep 21}{Move \cs{ifNAT@full} test from
+% \cs{NAT@parse} to here}
+% \changes{6.4}{1996 Oct 2}{Add dummy macros for \texttt{hyperref.sty}}
+% \changes{6.6}{1997 Jun 3}{Add sorting of citations}
+% \changes{6.7}{1997 Jul 16}{Add \cs{ifNAT@longnames} test}
+% \changes{7.0}{1999 May 7}{Suppress years when empty}
+% The author--year version of |\@citex| is now defined. It wants the authors
+% and year for each decoded label text to be separated into |\NAT@nm| and
+% |\NAT@date|. This is done by the routine |\NAT@parse|. The names of the
+% authors in the previous key are stored in |\NAT@last@nm|, and if that is the
+% same as the current names, it is not printed again. The output citation text
+% is not put into an |\hbox| since line division may occur within the
+% author--year citation. The output is formatted differently for parenthetical
+% (|\NAT@swa| \meta{true}) and textual (|\NAT@swa| \meta{false}) cases.
+%
+% The citation keys are in |#3|; these are sorted by |\NAT@sort@cites| and
+% stored in |\NAT@cite@list|. If sorting is turned off, this list is the same
+% as the original one.
+%
+% |\NAT@nm| will contain either |\NAT@name| or |\NAT@all@names| depending
+% on the state of |\ifNAT@full|.
+%
+% With the option \texttt{longnamesfirst}, the flag |\ifNAT@longnames| is
+% set; this makes the first citation of any reference use the long list of
+% names. The flag |\bv@|\meta{key} is defined after the first citation so
+% that short lists are used afterwards.
+%
+% When the year (|\NAT@date|) is empty, no year is printed, nor is the
+% preceding punctuation there; for textual citations, the brackets are also
+% suppressed. This is to allow to citations with a code designation without a
+% year.
+%
+% \begin{macrocode}
+%<subpack>\def\@citex%
+%<!subpack>\newcommand\NAT@citex{}
+%<!subpack>\def\NAT@citex%
+ [#1][#2]#3{%
+%<!209> \NAT@sort@cites{#3}%
+ \let\@citea\@empty
+ \@cite{\let\NAT@nm\@empty\let\NAT@year\@empty
+%<!209> \@for\@citeb:=\NAT@cite@list\do
+%<209> \@for\@citeb:=#3\do
+ {\edef\@citeb{\expandafter\@firstofone\@citeb}%
+ \if@filesw\immediate\write\@auxout{\string\citation{\@citeb}}\fi
+ \@ifundefined{b@\@citeb\@extra@b@citeb}{\@citea%
+%<209> {\reset@font\bf ?}\@warning
+%<!209> {\reset@font\bfseries ?}\NAT@citeundefined
+%<!209> \PackageWarning{natbib}%
+ {Citation `\@citeb' on page \thepage \space undefined}\def\NAT@date{}}%
+ {\let\NAT@last@nm=\NAT@nm\let\NAT@last@yr=\NAT@year
+ \NAT@parse{\@citeb}%
+%<*!subpack&!209>
+ \ifNAT@longnames\@ifundefined{bv@\@citeb\@extra@b@citeb}{%
+ \let\NAT@name=\NAT@all@names
+ \global\@namedef{bv@\@citeb\@extra@b@citeb}{}}{}%
+ \fi
+%</!subpack&!209>
+ \ifNAT@full\let\NAT@nm\NAT@all@names\else
+ \let\NAT@nm\NAT@name\fi
+% \end{macrocode}
+% Begin parenthetical citation. Check if author names the same as in the
+% previous citation, and if so, also check if the years are the same.
+% \changes{5.4}{1995 Feb 8}{Add \cs{unskip} to avoid double spacing
+% between years}
+% \changes{6.5}{1997 Jan 30}{Add optional notes for textual citations}
+% If so, citations are printed `1994a,b'; if a space is wanted between
+% the letters, as `1994a,~b', then give |\NAT@yrsep| as |{,~}|. For this
+% reason, the |\unskip| is needed when the space between years is printed
+% to avoid two spaces.
+%
+% \changes{6.6}{1997 May 17}{Add \cs{NAT@ctype} for author, year, or both}
+% This macro is to be used to define |\citep|, |\citet|, |\citeyear|, and
+% |\citeauthor|, controlled by various flags. The |\NAT@ctype| is a number
+% equal to 0 for author and year, 1 for author only, 2 for year only.
+% \changes{6.9}{1999 Jan 22}{Add citation alias feature}
+% A value of 3 is for the citation alias defined by |\defcitealias|.
+%
+% \changes{6.6}{1997 Jun 25}{Improve \texttt{hyperref} support}
+% \changes{6.6}{1997 Jun 30}{Add missing \cs{NAT@close} to \cs{@citea}}
+% \changes{6.7}{1997 Jul 14}{Put hyperlink brackets snuggly around
+% \cs{NAT@exlab} and \cs{NAT@date}}
+% \changes{6.8}{1998 Feb 19}{Remove superfluous \cs{hyper@natlinkstart}}
+% \changes{6.8b}{1998 July 2}{Add \cs{hyper@natlinkbreak}}
+% \changes{6.8c}{1998 July 14}{Remove opening brace and notes from link}
+% \changes{6.8c}{1998 July 14}{Add \cs{NAT@nmfmt}}
+% The hyperlinks are to bracket each reference completely, or at least that
+% part that is present. The author names and year are made into separate links
+% with the help of |\hyper@natlinkbreak|. Excluded from the link are
+% punctuation and space between names and year, as well as notes and braces.
+% Everything to be excluded is put into the first argument of |\hyper@natlinkbreak|.
+% (This needs \texttt{hyperref.sty} version~6.32.)
+%
+% Another aid to keeping links on one page is the |\NAT@nmfmt| function for
+% formatting names: normally this is nothing, but with the \texttt{nonamebreak}
+% option, it becomes |\mbox|. This was a special request.
+% \begin{macrocode}
+ \ifNAT@swa\ifcase\NAT@ctype
+ \if\relax\NAT@date\relax
+ \@citea\hyper@natlinkstart{\@citeb\@extra@b@citeb}%
+ \NAT@nmfmt{\NAT@nm}\NAT@date\hyper@natlinkend
+ \else
+ \ifx\NAT@last@nm\NAT@nm\NAT@yrsep
+ \ifx\NAT@last@yr\NAT@year
+ \hyper@natlinkstart{\@citeb\@extra@b@citeb}\NAT@exlab
+ \hyper@natlinkend
+ \else\unskip\
+ \hyper@natlinkstart{\@citeb\@extra@b@citeb}\NAT@date
+ \hyper@natlinkend
+ \fi
+ \else\@citea\hyper@natlinkstart{\@citeb\@extra@b@citeb}%
+ \NAT@nmfmt{\NAT@nm}%
+ \hyper@natlinkbreak{\NAT@aysep\ }{\@citeb\@extra@b@citeb}%
+ \NAT@date\hyper@natlinkend
+ \fi
+ \fi
+ \or\@citea\hyper@natlinkstart{\@citeb\@extra@b@citeb}%
+ \NAT@nmfmt{\NAT@nm}\hyper@natlinkend
+ \or\@citea\hyper@natlinkstart{\@citeb\@extra@b@citeb}%
+ \NAT@date\hyper@natlinkend
+%<*!209>
+ \or\@citea\hyper@natlinkstart{\@citeb\@extra@b@citeb}%
+ \NAT@alias\hyper@natlinkend
+%</!209>
+ \fi \def\@citea{\NAT@sep\ }%
+% \end{macrocode}
+% Begin textual citation. Do same checks for repeated names and years.
+% Optional notes are added here, not in |\NAT@cite|, which means for
+% multiple citations, each one will receive the notes in the year part.
+% (Pre-notes are questionable for this, but include them anyway.)
+% \changes{6.6}{1997 July 5}{Fix closing brace bug}
+% \begin{macrocode}
+ \else\ifcase\NAT@ctype
+ \if\relax\NAT@date\relax
+ \@citea\hyper@natlinkstart{\@citeb\@extra@b@citeb}%
+ \NAT@nmfmt{\NAT@nm}\hyper@natlinkend
+ \else
+ \ifx\NAT@last@nm\NAT@nm\NAT@yrsep
+ \ifx\NAT@last@yr\NAT@year
+ \hyper@natlinkstart{\@citeb\@extra@b@citeb}\NAT@exlab
+ \hyper@natlinkend
+ \else\unskip\
+ \hyper@natlinkstart{\@citeb\@extra@b@citeb}\NAT@date
+ \hyper@natlinkend
+ \fi
+ \else\@citea\hyper@natlinkstart{\@citeb\@extra@b@citeb}%
+ \NAT@nmfmt{\NAT@nm}%
+ \hyper@natlinkbreak{\ \NAT@@open\if*#1*\else#1\ \fi}%
+ {\@citeb\@extra@b@citeb}%
+ \NAT@date\hyper@natlinkend\fi
+ \fi
+ \or\@citea\hyper@natlinkstart{\@citeb\@extra@b@citeb}%
+ \NAT@nmfmt{\NAT@nm}\hyper@natlinkend
+ \or\@citea\hyper@natlinkstart{\@citeb\@extra@b@citeb}%
+ \NAT@date\hyper@natlinkend
+%<*!209>
+ \or\@citea\hyper@natlinkstart{\@citeb\@extra@b@citeb}%
+ \NAT@alias\hyper@natlinkend
+%</!209>
+ \fi \if\relax\NAT@date\relax\def\@citea{\NAT@sep\ }%
+ \else\def\@citea{\NAT@@close\NAT@sep\ }\fi
+ \fi
+ }}\ifNAT@swa\else\if*#2*\else\NAT@cmt#2\fi
+ \if\relax\NAT@date\relax\else\NAT@@close\fi\fi}{#1}{#2}}
+% \end{macrocode}
+%
+% \end{macro}\end{macro}
+%
+% \begin{macro}{\NAT@@open}
+% \changes{6.6}{1997 May 26}{Add macro}
+% \begin{macro}{\NAT@@close}
+% \changes{6.6}{1997 May 26}{Add macro}
+% To allow the opening and closing braces to be suppressed for |\citealt|, use
+% the flag |\ifNAT@par| in these macros. This only applies for author--year
+% mode.
+% \begin{macrocode}
+\newif\ifNAT@par \NAT@partrue
+\newcommand\NAT@@open{\ifNAT@par\NAT@open\fi}
+\newcommand\NAT@@close{\ifNAT@par\NAT@close\fi}
+% \end{macrocode}
+% \end{macro}\end{macro}
+%
+% \begin{macro}{\NAT@alias}
+% \changes{6.9}{1999 Jan 22}{Add macro}
+% When |\NAT@ctype| is 3, the citation alias previously defined with
+% |\defcitealias| is printed as the citation. This is a \LaTeXe\ feature only.
+% \begin{macrocode}
+%<*!209>
+\newcommand\NAT@alias{\@ifundefined{al@\@citeb\@extra@b@citeb}{%
+ {\reset@font\bfseries(alias?)}\PackageWarning{natbib}
+ {Alias undefined for citation `\@citeb'
+ \MessageBreak on page \thepage}}{\@nameuse{al@\@citeb\@extra@b@citeb}}}
+%</!209>
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\NAT@up}
+% \changes{7.0}{1999 May 10}{Add macro}
+% \begin{macro}{\NAT@Up}
+% \changes{7.0}{1999 May 10}{Add macro}
+% If a textual citation comes at the beginning of a sentence, and the first
+% author's name is with a von part, we want to be able to capitalize it. The
+% function |\NAT@up| precedes all names and is normally |\relax|, but can be
+% set to |\NAT@Up|, which capitalizes the first letter encountered. This even
+% works with old style font commands like |{\it van Burg}| but not with NFSS
+% commands like |\textit{van Burg}|. This is for use with the |\Citet|
+% command.
+% \begin{macrocode}
+\let\NAT@up\relax
+\newcommand\NAT@Up[1]{{\let\protect\@unexpandable@protect\let~\relax
+ \expandafter\NAT@deftemp#1}\expandafter\NAT@UP\NAT@temp}
+\newcommand\NAT@deftemp[1]{\xdef\NAT@temp{#1}}
+\newcommand\NAT@UP[1]{\let\@tempa\NAT@UP\ifcat a#1\MakeUppercase{#1}%
+ \let\@tempa\relax\else#1\fi\@tempa}
+% \end{macrocode}
+% \end{macro}\end{macro}
+%
+% \begin{macro}{\shortcites}
+% \changes{6.7}{1997 Jul 16}{Add macro}
+% In order to force selected citations to use short author lists even when
+% the |\ifNAT@longnames| flag is set, call this macro with a list of keys as
+% argument. It then defines the |\bv@| flags so that these citations do not
+% appear as `virginal'.
+% \begin{macrocode}
+%<*!subpack&!209>
+\newcommand\shortcites[1]{%
+ \@bsphack\@for\@citeb:=#1\do
+ {\edef\@citeb{\expandafter\@firstofone\@citeb}%
+ \global\@namedef{bv@\@citeb\@extra@b@citeb}{}}\@esphack}
+%</!subpack&!209>
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@biblabel}
+% \changes{5.5}{1995 Mar 21}{Is \cs{let} equal to the numerical or
+% author--year definition}
+% \changes{6.8}{1997 Dec 1}{Undefine original \cs{@biblabel}}
+% \begin{macro}{\NAT@biblabel}
+% \changes{5.5}{1995 Mar 21}{Renamed from \cs{@biblabel}}
+% \begin{macro}{\NAT@biblabelnum}
+% \changes{5.5}{1995 Mar 21}{Renamed from \cs{@biblabelnum}}
+% \begin{macro}{\bibnumfmt}
+% \changes{7.0}{1999 May 7}{Add macro}
+% Similarly for the |\@biblabel| command, that is used to format the
+% citation label in the list of references, define the author--year
+% and the numerical versions. For the former, no labels are
+% printed in the list of references.
+%
+% Suggestion by Donald Arseneau: undefined |\@biblabel| and have it set
+% to the predefined variants only if it is still undefined. This allows
+% users to redefine it themselves in the preamble using the standard
+% name. (They could redefine the |\NAT@biblabel|s but Arseneau figures
+% they should be able use the standard name too.)
+% The undefining is achieved by setting it to |\@empty|, not |\relax|
+% so that the user may still use |\renewcommand|. If the definition has
+% already been changed from the standard one, then leave it.
+%
+% And to simplify things for people who do not know about |\makeatletter|,
+% define |\NAT@biblabelnum| in terms of |\bibnumfmt|. One can still
+% redefine |\@biblabel| or even |\NAT@biblabelnum| if one wishes.
+%
+% \begin{macrocode}
+%<subpack>\renewcommand\@biblabel[1]{\hfill}
+%<*!subpack>
+\newcommand\NAT@biblabel[1]{\hfill}
+\newcommand\NAT@biblabelnum[1]{\bibnumfmt{#1}}
+\newcommand\bibnumfmt[1]{[#1]}
+\def\@tempa#1{[#1]}
+\ifx\@tempa\@biblabel\let\@biblabel\@empty\fi
+%</!subpack>
+% \end{macrocode}
+% \end{macro}\end{macro}\end{macro}\end{macro}
+%
+% \begin{macro}{\@bibsetup}
+% \changes{5.5}{1995 Mar 21}{Is \cs{let} equal to the numerical or
+% author--year definition}
+% \begin{macro}{\NAT@bibsetup}
+% \changes{5.5}{1995 Mar 13}{Add \cs{bibhang} for variable hanging
+% indentation}
+% \changes{5.5}{1995 Mar 21}{Renamed from \cs{@bibsetup}}
+% \begin{macro}{\NAT@bibsetnum}
+% \changes{5.1}{1994 Jun 22}{Add \cmd{\if@openbib} as in \LaTeXe}
+% \changes{5.5}{1995 Mar 21}{Renamed from \cs{@bibsetnum}}
+% \changes{6.1}{1995 Nov 22}{Use \cs{ifNAT@openbib}}
+% \changes{6.2}{1996 Mar 05}{Add \cs{bibsep} for linespacing between
+% references}
+% \changes{6.5}{1997 Jan 10}{Set \cs{bibsep} to 0 for EGS}
+% The macro |\@bibsetup| is called by |\thebibliography| and contains any
+% coding for formatting the list of references that may be different for
+% numerical and author--year schemes. For numerical citations, the
+% |\labelwidth| must be set to the size of the longest label (the argument
+% of |\thebibliography|), and the |\leftmargin| adjusted accordingly. For
+% author--year, there are no labels, so |\labelwidth| is zero, all lines
+% after the first are indented by 1~em.
+%
+% Since |\thebibliography| is not included in the \textsl{AGU} package,
+% this macro is left off here too.
+% \begin{macrocode}
+%<*!agu>
+%<*!egs>
+%<*!subpack>
+\newcommand\NAT@bibsetnum[1]{\settowidth\labelwidth{\@biblabel{#1}}%
+ \setlength{\leftmargin}{\labelwidth}\addtolength{\leftmargin}{\labelsep}%
+ \setlength{\itemsep}{\bibsep}\setlength{\parsep}{\z@}%
+%<*!209>
+ \ifNAT@openbib
+ \addtolength{\leftmargin}{\bibindent}%
+ \setlength{\itemindent}{-\bibindent}%
+ \setlength{\listparindent}{\itemindent}%
+ \setlength{\parsep}{0pt}%
+ \fi
+%</!209>
+}
+%</!subpack>
+%</!egs>
+\newlength{\bibhang}
+\setlength{\bibhang}{1em}
+% \end{macrocode}
+%
+% The length |\bibsep| is to be the spacing between listed references.
+% This is normally the regular line spacing between |\item|s in a
+% \texttt{list} environment, which is |\itemsep| + |\parsep|. These are set
+% by |\@listi|. Therefore, in order to set |\bibsep| to the default value,
+% call |\@listi| locally and globally set it.
+%
+% \begin{macrocode}
+\newlength{\bibsep}
+%<!egs>{\@listi \global\bibsep\itemsep \global\advance\bibsep by\parsep}
+%<egs>\setlength{\bibsep}{\z@}
+
+%<subpack>\newcommand\@bibsetup%
+%<!subpack>\newcommand\NAT@bibsetup%
+ [1]{\setlength{\leftmargin}{\bibhang}\setlength{\itemindent}{-\leftmargin}%
+ \setlength{\itemsep}{\bibsep}\setlength{\parsep}{\z@}}
+%</!agu>
+% \end{macrocode}
+% \end{macro}\end{macro}\end{macro}
+%
+% \begin{macro}{\NAT@set@cites}
+% \changes{5.5}{1995 Mar 21}{New macro to set the internal macros to
+% numerical or author--year}
+% \changes{6.3}{1996 Jun 17}{Add \cs{natexlab}}
+% \changes{6.4}{1996 Sep 12}{Remove \cs{global} from definitions and \cs{let}}
+% \changes{6.4}{1996 Sep 12}{Define \cs{NAT@space} differently for
+% numericals and superscripts}
+% \changes{6.6}{1997 Jun 4}{Define \cs{NAT@mbox} for superscripts}
+% \changes{6.8}{1997 Dec 1}{Allow user redefinition of \cs{@biblabel}}
+% \changes{6.8a}{1998 May 14}{\cs{@biblabel} redefined only for numericals}
+% The four internal macros that have different definitions depending on the
+% citation style have been defined with different names; now set the macros
+% to be executed to that set that is actually wanted. This is determined by
+% the flags |\ifNAT@numbers| and |\ifNAT@super|. The setting command
+% |\NAT@set@cites| is executed by |\begin{document}|, after which point,
+% the citation style should be frozen.
+%
+% The command |\natexlab| is used in the \texttt{.bst} files to enclose the
+% extra labels (the letters added to the dates); these are to be suppressed
+% for numerical citations.
+% \begin{macrocode}
+%<*!subpack>
+\newcommand\NAT@set@cites{\ifNAT@numbers
+ \ifNAT@super \let\@cite\NAT@citesuper
+ \def\NAT@mbox##1{\unskip\nobreak\hspace{1\p@}\textsuperscript{##1}}%
+ \let\citeyearpar=\citeyear
+ \let\NAT@space\relax\else
+ \let\NAT@mbox=\mbox
+ \let\@cite\NAT@citenum \def\NAT@space{ }\fi
+ \let\@citex\NAT@citexnum
+ \ifx\@biblabel\@empty\let\@biblabel\NAT@biblabelnum\fi
+ \let\@bibsetup\NAT@bibsetnum
+ \def\natexlab##1{}%
+ \else
+ \let\@cite\NAT@cite
+ \let\@citex\NAT@citex
+ \let\@biblabel\NAT@biblabel
+ \let\@bibsetup\NAT@bibsetup
+ \def\natexlab##1{##1}%
+ \fi}
+%<!209>\AtBeginDocument{\NAT@set@cites}
+%</!subpack>
+% \end{macrocode}
+% \end{macro}
+%
+% \changes{6.5}{1997 Jan 30}{Add \texttt{showkeys} coding for \cs{@citex}}
+% Since |\citep|, |\citet|, and |\citealt| are all ultimately defined in
+% terms of the |\@citex| command, the best way to get the \texttt{showkeys}
+% package to handle these is to let it accommodate only |\@citex|. David
+% Carlisle has allowed for \thestyle, but only for |\cite| with variable number
+% of arguments, |\citeauthor|, |\citefullauthor|, and |\citeyear|. Add the
+% necessary coding at the beginning, after we know if \texttt{showkeys}
+% has been loaded or not, and |\@citex| has its final definition.
+%
+% \changes{6.6}{1997 May 27}{Allow \texttt{notcite} option with
+% \texttt{showkeys} package; turn off special coding}
+% Paradoxically, with version~6.6 it is necessary to remove the special coding
+% in \texttt{showkeys} for \thestyle. Now all |\cite..| commands are defined in
+% terms of |\@citex|, so that is sufficient, and the special coding is now
+% incorrect. This means resetting special coding for |\citeauthor|,
+% |\citefullauthor|, |\citeyear|. Alternatively, define |\HAR@checkdef|
+% which then also skips special \thestyle\ coding. It is just a question of
+% which package is loaded first.
+%
+% There is no point asking Carlisle to add |\@citex| to \texttt{showkeys}
+% because \thestyle\ fixes this macro with |\begin{document}|; thus
+% \texttt{showkeys} would have to be loaded \emph{after} \thestyle. By
+% including the recoding of |\@citex| here, it is not dependent on the order of
+% the two packages.
+%
+% \changes{6.7}{1997 Sep 12}{Replace \cs{@ifpackageloaded} for
+% \texttt{showkeys}}
+% If the \texttt{showkeys} package is loaded with option \texttt{final}, its
+% coding is not loaded. This is meant to shutoff the package after the draft
+% version. However, \thestyle\ (version~6.6 and earlier) was confused by this,
+% because it only tested if the package was loaded, not if its coding was active.
+% Version~6.7 no longer uses |\@ifpackageloaded{showkeys}| for this test, but
+% tests if |\SK@def| exists (suggestion by David Carlisle).\label{SKdef}
+%
+% \begin{macrocode}
+%<*!209>
+\AtBeginDocument{\ifx\SK@def\@undefined\else
+\ifx\SK@cite\@empty\else
+ \SK@def\@citex[#1][#2]#3{\SK@\SK@@ref{#3}\SK@@citex[#1][#2]{#3}}\fi
+\ifx\SK@citeauthor\@undefined\def\HAR@checkdef{}\else
+ \let\citeauthor\SK@citeauthor
+ \let\citefullauthor\SK@citefullauthor
+ \let\citeyear\SK@citeyear\fi
+\fi}
+% \end{macrocode}
+%
+% With the \texttt{hyperref} package, compression of numerical citations
+% must be turned off.
+% \begin{macrocode}
+%<*!subpack>
+\AtBeginDocument{\@ifpackageloaded{hyperref}{%
+ \ifnum\NAT@sort=2\def\NAT@sort{1}\fi}{}}
+%</!subpack>
+%</!209>
+% \end{macrocode}
+%
+% \subsection{The Citations}
+%
+% \begin{macro}{\citet}
+% \changes{6.2}{1996 Jan 11}{Add macro for textual cite in numerical mode}
+% \changes{6.5}{1997 Jan 30}{Make this standard textual citation, with notes}
+% \changes{6.6}{1997 May 26}{Define with \cs{ifNAT@par} on}
+% \changes{6.6}{1997 May 27}{Redefine for new coding of \cs{@citex}}
+% \changes{6.8}{1998 Feb 19}{Place inside a group}
+% Textual citations are made with the |\citet| command, which has a starred
+% form for full authors, and may have one or two optional arguments for notes.
+%
+% This command is equivalent to the older syntex |\cite|\marg{key} without
+% optional arguments, at least in author--year mode. In numerical mode,
+% it prints the authors and then the numerical reference, whereas |\cite|
+% will only print the number. This simplifies the switching between the two
+% modes with minimal changes in text. One wants to replace ``as shown by Jones
+% et~al.\ (1990)'' with ``as shown by Jones et~al.\ [21]''; with |\cite|,
+% one would get ``as shown by [21]''.
+%
+% This is such a practical idea, that I have decided to make it the standard
+% means of textual citing. It now even allows optional notes in textual cites,
+% something that I have been asked to provide, and which is impossible under
+% the old syntex with |\cite|.
+%
+% Note that the flag |\ifNAT@swa| determines if the citation is textual or
+% parenthetical, and |\ifNAT@full| whether abbreviated or full author names
+% are to be printed.
+% The flag |\ifNAT@par| enables the opening and closing parentheses; this is
+% used only to suppress these for |\citealt| below.
+%
+% The flag |\NAT@ctype| controls what |\@citex| actually outputs: author and
+% year (0), author only (1), year only (2). (For numerical mode, 0 yields
+% author [number].)
+%
+% All the citation commands are placed inside a group; they start
+% with |\begingroup|, with the corresponding |\endgroup| added to
+% the |\@cite| command. This localizes the flag settings so that cites may
+% be contained with cites, as
+% \begin{quote}
+% |\citep[cited in \citealp{xx}]{yy}|
+% \end{quote}
+% (Without the localization, the |\citealp| turns off the brackets before
+% |\citep| comes to an end.)
+% \begin{macrocode}
+\newif\ifNAT@full\NAT@fullfalse
+\newif\ifNAT@swa
+%<209>\newcommand\citet
+%<!209>\DeclareRobustCommand\citet
+ {\begingroup\NAT@swafalse\def\NAT@ctype{0}\NAT@partrue
+ \@ifstar{\NAT@fulltrue\NAT@citetp}{\NAT@fullfalse\NAT@citetp}}
+\newcommand\NAT@citetp{\@ifnextchar[{\NAT@@citetp}{\NAT@@citetp[]}}
+\newcommand\NAT@@citetp{}
+\def\NAT@@citetp[#1]{\@ifnextchar[{\@citex[#1]}{\@citex[][#1]}}
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\citep}
+% \changes{5.5}{1995 Mar 27}{Add macro as shorthand for \cs{cite[]}}
+% \changes{6.5}{1997 Jan 30}{Make this standard parenthetical citation,
+% with notes}
+% \changes{6.6}{1997 May 26}{Define with \cs{ifNAT@par} on}
+% \changes{6.6}{1997 May 27}{Redefine for new coding of \cs{@citex}}
+% \changes{6.8}{1998 Feb 19}{Place inside a group}
+% Parenthetical citations are made with the |\citep| command, which has a
+% starred form for full authors, and may have one or two optional arguments for
+% notes.
+%
+% This command was originally added by special request to be a simplification
+% for |\cite[]|\marg{key}, and I added it grudgingly. After I reprogrammed
+% \thestyle\ to handle author--year and numerical citations with the same
+% \texttt{.bst} file, I needed to add the |\citet| command, and this one
+% became an obvious companion for parenthetical citations. I have now altered
+% its coding to be the standard, being fully equivalent in functionality
+% to the older syntax |\cite|\oarg{pre}\oarg{post}\marg{key}.
+% \begin{macrocode}
+%<209>\newcommand\citep
+%<!209>\DeclareRobustCommand\citep
+ {\begingroup\NAT@swatrue\def\NAT@ctype{0}\NAT@partrue
+ \@ifstar{\NAT@fulltrue\NAT@citetp}{\NAT@fullfalse\NAT@citetp}}
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\cite}
+% \changes{5.0}{1994 May 18}{Add a second optional argument.}
+% \changes{5.3}{1994 Sep 19}{Add starred version to print full author list.}
+% \changes{5.4}{1994 Nov 24}{Replace \cmd{\if@tempswa} with \cmd{\ifNAT@swa}.}
+% \changes{6.5}{1997 Jan 30}{Declare obsolete, retained for compatibility}
+% \changes{6.6}{1997 May 27}{Redefine for new coding of \cs{@citex}}
+% \changes{6.8}{1998 Feb 19}{Place inside a group}
+% The |\cite| command was originally used to produce both textual and
+% parenthetical citations; with an option argument, even an empty one,
+% the citation was parenthical. I now recommend the use of |\citet| and
+% |\citep| instead, retaining |\cite| only for compatibility.
+%
+% In numerical mode, it must be parenthetical (|ifNAT@swa| \meta{true}) both
+% with and without notes, so that it emulates the standard \LaTeX\ usage. In
+% author--year mode, this flag depends on presence or absence of notes.
+% \begin{macrocode}
+%<209>\renewcommand\cite
+%<!209>\DeclareRobustCommand\cite
+ {\begingroup\def\NAT@ctype{0}\NAT@partrue\NAT@swatrue
+ \@ifstar{\NAT@fulltrue\NAT@cites}{\NAT@fullfalse\NAT@cites}}
+\newcommand\NAT@cites{\@ifnextchar [{\NAT@@citetp}{%
+%<!subpack> \ifNAT@numbers\else
+ \NAT@swafalse
+%<!subpack> \fi
+ \NAT@@citetp[]}}
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\citealt}
+% \changes{5.5}{1995 Mar 16}{Add macro}
+% \changes{6.5}{1997 Jan 30}{Uses \cs{citet} instead of \cs{cite}}
+% \changes{6.6}{1997 May 26}{Define as \cs{citet} but with \cs{NAT@par} off}
+% \changes{6.8}{1998 Feb 19}{Place inside a group}
+% \changes{7.0}{1999 May 21}{Include in subpack}
+% \begin{macro}{\citealp}
+% \changes{6.6}{1997 Jun 23}{Add macro, like \cs{citep} without parentheses}
+% \changes{6.8}{1998 Feb 19}{Place inside a group}
+% \changes{7.0}{1999 May 21}{Include in subpack}
+% An alternative form of citation is one in which the parentheses are not
+% printed. This was originally requested by Alexander Holt, who wanted it to be
+% the same as |\citet| but without any braces; since then James Bednar has asked
+% that it behave exactly as the other |\cite|\emph{xxx}, including notes, to
+% allow easy switching between the two possibilities. It is now defined with the
+% help of the flags |\ifNAT@swa| and |\ifNAT@par| to be the same as |\citet|;
+% to accommodate the more sensible |\citep| without parentheses, I now provide
+% |\citealp|.
+%
+% I can see using |\citealp| where one wants to construct a complex
+% parenthetical reference by hand, explicitly adding the braces. Thus
+% it makes sense to have this feature work in numerical mode too.
+% As of version~6.8, this is possible. The two macros |\NAT@cite| and
+% |\NAT@citenum| are identical, but kept anyway just in case a difference
+% should be added later.
+% \begin{macrocode}
+%<209>\newcommand\citealt
+%<!209>\DeclareRobustCommand\citealt
+ {\begingroup\NAT@swafalse\def\NAT@ctype{0}\NAT@parfalse
+ \@ifstar{\NAT@fulltrue\NAT@citetp}{\NAT@fullfalse\NAT@citetp}}
+%<209>\newcommand\citealp
+%<!209>\DeclareRobustCommand\citealp
+ {\begingroup\NAT@swatrue\def\NAT@ctype{0}\NAT@parfalse
+ \@ifstar{\NAT@fulltrue\NAT@citetp}{\NAT@fullfalse\NAT@citetp}}
+% \end{macrocode}
+% \end{macro}\end{macro}
+%
+% \begin{macro}{\citeauthor}
+% \changes{5.0}{1994 May 18}{Add means to cite authors only.}
+% \changes{5.2}{1994 Aug 25}{Enclose \cs{@citenm} in braces.}
+% \changes{5.2}{1994 Aug 25}{Add auxiliary file entry.}
+% \changes{6.0}{1995 Sep 4}{Check for empty author}
+% \changes{6.4}{1996 Oct 2}{Add dummy macros for \texttt{hyperref.sty}}
+% \changes{6.6}{1997 May 27}{Define with \cs{@citex} and \cs{NAT@ctype}}
+% \changes{6.8}{1998 Feb 19}{Place inside a group}
+% In order to refer to the authors without year or number, provide
+% |\citeauthor| and |\citeauthor*|; for historical reasons, keep
+% |\citefullauthor|.
+% \begin{macrocode}
+%<209>\newcommand\citeauthor
+%<!209>\DeclareRobustCommand\citeauthor
+ {\begingroup\NAT@swafalse\def\NAT@ctype{1}\NAT@parfalse
+ \@ifstar{\NAT@fulltrue\NAT@citetp}{\NAT@fullfalse\NAT@citetp}}
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\Citet}
+% \changes{7.0}{1999 May 10}{Add macro}
+% \begin{macro}{\Citep}
+% \changes{7.0}{1999 May 10}{Add macro}
+% \begin{macro}{\Citealt}
+% \changes{7.0}{1999 May 10}{Add macro}
+% \begin{macro}{\Citealp}
+% \changes{7.0}{1999 May 10}{Add macro}
+% \begin{macro}{\Citeauthor}
+% \changes{7.0}{1999 May 10}{Add macro}
+% When a textual citation occurs at the beginning of a sentence and the first
+% name is something like ``de la Maire'', it needs to be capitalized. This is
+% done with the |\NAT@up| command that is redefined to be |\NAT@Up|.
+%
+% Provide other variations too for completeness. If I do not, someone will
+% eventually ask for it, so do it now.
+% \begin{macrocode}
+%<209>\newcommand\Citet
+%<!209>\DeclareRobustCommand\Citet
+ {\begingroup\NAT@swafalse\def\NAT@ctype{0}\NAT@partrue
+ \let\NAT@up\NAT@Up
+ \@ifstar{\NAT@fulltrue\NAT@citetp}{\NAT@fullfalse\NAT@citetp}}
+%<209>\newcommand\Citep
+%<!209>\DeclareRobustCommand\Citep
+ {\begingroup\NAT@swatrue\def\NAT@ctype{0}\NAT@partrue
+ \let\NAT@up\NAT@Up
+ \@ifstar{\NAT@fulltrue\NAT@citetp}{\NAT@fullfalse\NAT@citetp}}
+%<*!subpack>
+%<209>\newcommand\Citealt
+%<!209>\DeclareRobustCommand\Citealt
+ {\begingroup\NAT@swafalse\def\NAT@ctype{0}\NAT@parfalse
+ \let\NAT@up\NAT@Up
+ \@ifstar{\NAT@fulltrue\NAT@citetp}{\NAT@fullfalse\NAT@citetp}}
+%<209>\newcommand\Citealp
+%<!209>\DeclareRobustCommand\Citealp
+ {\begingroup\NAT@swatrue\def\NAT@ctype{0}\NAT@parfalse
+ \let\NAT@up\NAT@Up
+ \@ifstar{\NAT@fulltrue\NAT@citetp}{\NAT@fullfalse\NAT@citetp}}
+%</!subpack>
+%<209>\newcommand\Citeauthor
+%<!209>\DeclareRobustCommand\Citeauthor
+ {\begingroup\NAT@swafalse\def\NAT@ctype{1}\NAT@parfalse
+ \let\NAT@up\NAT@Up
+ \@ifstar{\NAT@fulltrue\NAT@citetp}{\NAT@fullfalse\NAT@citetp}}
+% \end{macrocode}
+% \end{macro}\end{macro}\end{macro}\end{macro}\end{macro}
+%
+% \begin{macro}{\citeyear}
+% \changes{5.0}{1994 May 18}{Add means to cite year only.}
+% \changes{5.2}{1994 Aug 25}{Add auxiliary file entry.}
+% \changes{6.0}{1995 Sep 4}{Check for empty year}
+% \changes{6.4}{1996 Sep 12}{Extra letter also printed with year number}
+% \changes{6.4}{1996 Oct 2}{Add dummy macros for \texttt{hyperref.sty}}
+% \changes{6.6}{1997 May 27}{Define with \cs{@citex} and \cs{NAT@ctype}}
+% \changes{6.8}{1998 Feb 19}{Place inside a group}
+% Similarly for the year only.
+% \begin{macrocode}
+%<209>\newcommand\citeyear
+%<!209>\DeclareRobustCommand\citeyear
+ {\begingroup\NAT@swafalse\def\NAT@ctype{2}\NAT@parfalse\NAT@citetp}
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\citeyearpar}
+% \changes{6.6}{1997 May 17}{Add macro}
+% \changes{6.8}{1998 Feb 19}{Place inside a group}
+% I have often been asked for a version of |\citeyear| in parentheses.
+% \begin{macrocode}
+%<209>\newcommand\citeyearpar
+%<!209>\DeclareRobustCommand\citeyearpar
+ {\begingroup\NAT@swatrue\def\NAT@ctype{2}\NAT@partrue\NAT@citetp}
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\citetext}
+% \changes{6.8}{1998 Feb 19}{Add macro}
+% To place any arbitrary text inside the citation braces, use |\citetext|.
+% This can be used to advantage with |\citealp|. It also makes |\citeyearpar|
+% unnecessary.
+% \begin{macrocode}
+\newcommand\citetext[1]{\NAT@open#1\NAT@close}
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\citefullauthor}
+% \changes{5.3}{1994 Sep 13}{Add macro for those bib styles with full author
+% list available}
+% \changes{6.0}{1995 Sep 4}{Check for empty author}
+% \changes{6.4}{1996 Oct 2}{Add dummy macros for \texttt{hyperref.sty}}
+% \changes{6.6}{1997 May 27}{Define with \cs{citeauthor*}}
+% Some of the author--year bibliography styles supported here (\texttt{harvard}
+% and \texttt{newapa}) allow a citation with the full author list, because
+% they have the necessary information in the |\bibitem| entry. With
+% version~5.3, I change the native form of this entry to allow
+% full authors too.
+%
+% This is now defined in terms of the starred version of |\citeauthor|. It is
+% really only kept for compatibility reasons.
+% \begin{macrocode}
+%<209>\newcommand\citefullauthor
+%<!209>\DeclareRobustCommand\citefullauthor
+ {\citeauthor*}
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\defcitealias}
+% \changes{6.9}{1999 Jan 22}{Add macro}
+% \begin{macro}{\citetalias}
+% \changes{6.9}{1999 Jan 22}{Add macro}
+% \begin{macro}{\citepalias}
+% \changes{6.9}{1999 Jan 22}{Add macro}
+% An alias is an alternative designation for a reference, something like [ABG]
+% in place of [Alpher, Bethe, Gamow, 1980]. The alias is defined with
+% |\defcitealias| and used with |\citetalias| and |\citepalias|.
+% This is controlled with
+% |\NAT@ctype| set to 3. This feature only exists for \LaTeXe.
+%
+% The advantage over simply typing in the alias name is that hyperlinks and
+% indexing can be achieved.
+% \begin{macrocode}
+%<*!209>
+\newcommand\defcitealias[2]{%
+ \@ifundefined{al@#1\@extra@b@citeb}{}
+ {\PackageWarning{natbib}{Overwriting existing alias for citation #1}}
+ \@namedef{al@#1\@extra@b@citeb}{#2}}
+\DeclareRobustCommand\citetalias{\begingroup
+ \NAT@swafalse\def\NAT@ctype{3}\NAT@parfalse\NAT@citetp}
+\DeclareRobustCommand\citepalias{\begingroup
+ \NAT@swatrue\def\NAT@ctype{3}\NAT@partrue\NAT@citetp}
+%</!209>
+% \end{macrocode}
+% \end{macro}\end{macro}\end{macro}
+%
+% \begin{macro}{\nocite}
+% \changes{6.6}{1997 Apr 6}{Revise standard macro}
+% In \LaTeXe, the |\nocite| command issues a warning if the citations are not
+% defined. This is a check to see that they really are entered into the list
+% of references. However, the |\@extra@b@citeb| addition for the
+% \texttt{chapterbib} package is not allowed for, and hence the standard
+% command will never recognize the citations as being defined. Modify the
+% macro accordingly. Check for |*| citation, in which case, give no warning.
+% \begin{macrocode}
+\renewcommand\nocite[1]{\@bsphack
+ \@for\@citeb:=#1\do{%
+ \edef\@citeb{\expandafter\@firstofone\@citeb}%
+ \if@filesw\immediate\write\@auxout{\string\citation{\@citeb}}\fi
+ \if*\@citeb\else
+ \@ifundefined{b@\@citeb\@extra@b@citeb}{%
+%<209> \@warning
+%<!209> \NAT@citeundefined \PackageWarning{natbib}%
+ {Citation `\@citeb' undefined}}{}\fi}%
+ \@esphack}
+% \end{macrocode}
+% \end{macro}
+%
+% \subsection{Parsing the Author--Year Entries}
+% \begin{macro}{\NAT@parse}
+% \changes{5.0}{1994 May 18}{Add parsing command, with additional
+% font and sub-accent commands relaxed}
+% \changes{5.1}{1994 Jun 22}{For \LaTeXe{} of \texttt{1994/06/01},
+% can protect font and sub-accents much better}
+% \changes{5.2}{1994 Aug 24}{2.09 version to run in compatibility mode}
+% \changes{5.3}{1994 Sep 13}{Add full author list}
+% \changes{5.3}{1994 Sep 19}{Support starred version of \cs{cite} for full
+% author list}
+% \changes{5.3}{1994 Sep 26}{Use \cs{@unexpandable@protect} in place of
+% \cs{noexpand}}
+% \changes{5.4}{1995 Feb 6}{Call \cs{@parse@date} to split date into year and
+% extra label}
+% \changes{5.5}{1995 May 18}{Rename from \cs{@cite@parse}}
+% \changes{6.0}{1995 Sep 4}{Remove \cs{relax} from expanded \cs{@tempa}
+% definition; no longer needed under new system}
+% \changes{6.0}{1995 Sep 21}{Prevent expansion of forced space (tilde)}
+% \changes{6.7}{1997 Nov 10}{Deactive \texttt{babel}'s \cs{active@prefix}}
+% The |\bibcite| commands in the auxiliary file associate the numerical and
+% author--year information with the |\bibitem| key, which is the argument to
+% |\NAT@parse|. As of version~6.0, the information is stored in
+% |\b@|\emph{key} for each citation, as four separate items.
+% \begin{quote}\begin{tabular}{lll}
+% 1. & |\NAT@num| & sequence number or non-author--year label \\
+% 2. & |\NAT@date| & year, with possible extra label \\
+% 3. & |\NAT@name| & short author list \\
+% 4. & |\NAT@all@names| & long author list (optional)
+% \end{tabular}\end{quote}
+% In order to define each of the above commands as the appropriate item, it
+% is first necessary to expand |\b@|\emph{key} into a temporary command
+% |\NAT@temp|, which is then used as the argument of |\NAT@split|, which
+% makes the individual assignments.
+% \begin{macrocode}
+\newcommand\NAT@parse[1]{{%
+%<*209>
+ \@ifundefined{documentclass}
+ {\let\prm=\relax\let\psf=\relax\let\ptt=\relax\let\pbf=\relax
+ \let\psl=\relax\let\psc=\relax\let\pit=\relax\let\pem=\relax
+ \let\prmfamily=\relax\let\psffamily=\relax\let\pttfamily=\relax
+ \let\pbfseries=\relax\let\pslshape=\relax\let\pscshape=\relax
+ \let\pitshape=\relax\let\pmdseries=\relax\let\pupshape=\relax
+ \let\pc=\relax \let\pd=\relax \let\pb=\relax}
+ {\let\protect=\@unexpandable@protect\let~\relax}%
+%</209>
+%<!209> \let\protect=\@unexpandable@protect\let~\relax
+%<!209> \let\active@prefix=\@gobble
+ \xdef\NAT@temp{\csname b@#1\@extra@b@citeb\endcsname}}%
+ \expandafter\NAT@split\NAT@temp
+ \expandafter\NAT@parse@date\NAT@date??????@@%
+%<!subpack&!209> \ifciteindex\NAT@index\fi
+}
+% \end{macrocode}
+% Some further notes on the above: for 2.09 it is necessary to turn off all the
+% protected font commands |\prm| etc.\ when the label text is expanded into
+% |\NAT@temp|, for otherwise there will be problems with the New Font
+% Selection Scheme (NFSS); the protected sub-accent commands (protected
+% versions of |\c|, |\d|, and |\b|) also cause troubles on expansion.
+% Admittedly, this is not a good solution, for the list of problem commands
+% might be much longer, but for the meantime, this will have to do.
+%
+% For \LaTeXe, at least after the official release of
+% \texttt{1994/06/01}, commands are made robust in a totally different
+% manner, no longer by adding a \texttt{p} in front, but by adding a space
+% afterwards. This means the commands in the auxiliary files look like the
+% protected version once again, and not raw commands. They are infinitely
+% protected. The above problem is easily overcome by making |\protect|
+% equal to |\@unexpandable@protect|. A definitive list of commands to
+% protect is no longer necessary. (Initially I used |\noexpand|, but
+% that only worked for font commands, not accents. Reading the documentation
+% in \texttt{ltdefns.dtx} indicated that this is the better redefinition
+% of |\protect|.)
+%
+% This trick is also applied to the 2.09 version for when it is running
+% in the compatibility mode of \LaTeXe. This is needed for the
+% journal-specific coding, more than for the normal package.
+%
+% The |\active@prefix| command appearing in \texttt{babel} causes problems
+% at this point, so deactivate it.
+%
+% The automatic indexing of citations (|\NAT@index|) is described in
+% Section~\ref{sec:idx}.
+%
+% \end{macro}
+%
+% \begin{macro}{\NAT@split}
+% \changes{5.3}{1994 Sep 13}{Changed to support full author list}
+% \changes{5.5}{1995 May 14}{Fix coding slightly}
+% \changes{5.5}{1995 May 18}{Renamed from \cs{@citez}}
+% \changes{6.0}{1995 Sep 4}{Recode for new \cs{bibcite} structure}
+% The actual assignments of the author--year and numerical label texts to
+% the corresponding commands is carried out by |\NAT@split|. If the long
+% author list is missing (argument |#4|), it is set equal to the short
+% list.
+% \begin{macrocode}
+\newcommand\NAT@split[4]{%
+ \gdef\NAT@num{#1}\gdef\NAT@name{#3}\gdef\NAT@date{#2}%
+ \gdef\NAT@all@names{#4}%
+ \ifx\NAT@noname\NAT@all@names \gdef\NAT@all@names{#3}\fi}
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\NAT@parse@date}
+% \changes{5.4}{1995 Feb 6}{Add macro to split date into year and extra label}
+% \changes{5.5}{1995 Mar 24}{Put extra label in braces to localize any font
+% changes}
+% \changes{5.5}{1995 May 18}{Rename from \cs{@parse@date}}
+% With version 5.4, add the macro |\NAT@parse@date| that splits the date up
+% into year and extra label, putting them into |\NAT@year| and |\NAT@exlab|.
+% This is used to test if authors and years are equal for two adjacent
+% citations, in which case, only the extra label is printed. The
+% macro searches the first 4 characters of the date for a letter
+% (|\catcode|=11) which then becomes the extra label. If there are only
+% numerals in the first 4 positions (more precisely, non-letters), the 5th
+% character is taken as extra label. If there is none, this will be a
+% question mark.
+% \begin{macrocode}
+\newcommand\NAT@parse@date{}
+\def\NAT@parse@date#1#2#3#4#5#6@@{%
+ \ifnum\the\catcode`#1=11\def\NAT@year{}\def\NAT@exlab{#1}\else
+ \ifnum\the\catcode`#2=11\def\NAT@year{#1}\def\NAT@exlab{#2}\else
+ \ifnum\the\catcode`#3=11\def\NAT@year{#1#2}\def\NAT@exlab{#3}\else
+ \ifnum\the\catcode`#4=11\def\NAT@year{#1#2#3}\def\NAT@exlab{#4}\else
+ \def\NAT@year{#1#2#3#4}\def\NAT@exlab{{#5}}\fi\fi\fi\fi}
+% \end{macrocode}
+% \end{macro}
+%
+% \subsection{Automatic Index Entries for Citations}\label{sec:idx}
+%
+% \begin{macro}{\NAT@idxtxt}
+% \changes{6.0}{1995 Sep 21}{Add macro}
+% \begin{macro}{\NAT@index}
+% \changes{6.0}{1995 Sep 21}{Add macro}
+% \changes{6.9}{1999 Jan 22}{Allow \cs{makeindex} to be issued before package
+% loaded}
+% To make an entry in the index for every citation, I have added
+% |\NAT@index| to the |\NAT@parse| command. This will do nothing unless
+% |\makeindex| has been issued in the preamble, in which case it writes the
+% citation information to the \texttt{.idx} file by means of the standard
+% \LaTeX\ internal |\@wrindex|. The actual format of the citation
+% information is contained in |\NAT@idxtxt| which a user may redefine if
+% needed.
+% \begin{macrocode}
+%<*!subpack&!209>
+\newcommand\NAT@index{}
+\let\NAT@makeindex=\makeindex
+\renewcommand\makeindex{\NAT@makeindex
+ \renewcommand\NAT@index{\@bsphack\begingroup
+ \def~{\string~}\@wrindex{\NAT@idxtxt}}}
+\newcommand\NAT@idxtxt{\NAT@name\ \NAT@open\NAT@date\NAT@close}
+% \end{macrocode}
+% If |\makeindex| has already been issued before \thestyle\ is loaded, it
+% does not contain these extra features. Thus issue it once more, but only with
+% the extra features.
+% \begin{macrocode}
+\@ifundefined{@indexfile}{}{\let\NAT@makeindex\relax\makeindex}
+% \end{macrocode}
+% \end{macro}\end{macro}
+% \begin{macro}{\ifciteindex}
+% \changes{6.0}{1995 Sep 21}{Add flag}
+% The switch for activating automatic citation indexing is defined here.
+% \begin{macrocode}
+\newif\ifciteindex \citeindexfalse
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\citeindextype}
+% \changes{6.0}{1995 Sep 29}{Add macro}
+% \begin{macro}{\NAT@index@alt}
+% \changes{6.0}{1995 Sep 29}{Add macro}
+% The above coding will not work with the package \texttt{index.sty} by
+% David~M. Jones. For that package, an alternative definition of |\NAT@index|
+% is needed which is activated at the beginning of the document if
+% \texttt{index} has been loaded. It thus does not matter in which order
+% \thestyle\ or \texttt{index} are loaded.
+%
+% With the \texttt{index} package, it is possible to have several index
+% files, defined by a |\newindex| command that associates a name with two
+% file extensions. By default, the name \texttt{default} is associated with
+% \texttt{.idx} and \texttt{.ind}. To make the automatic index entries go to
+% a different set, redefine |\citeindextype|.
+%
+% \begin{macrocode}
+\newcommand\citeindextype{default}
+\newcommand\NAT@index@alt{{\let\protect=\noexpand\let~\relax
+ \xdef\NAT@temp{\NAT@idxtxt}}\expandafter\NAT@exp\NAT@temp\@nil}
+\newcommand\NAT@exp{}
+\def\NAT@exp#1\@nil{\index[\citeindextype]{#1}}
+
+\AtBeginDocument{%
+\@ifpackageloaded{index}{\let\NAT@index=\NAT@index@alt}{}}
+%</!subpack&!209>
+% \end{macrocode}
+% \end{macro}\end{macro}
+%
+% \subsection{Writing the Entries to the Auxiliary File}
+%
+% \noindent(New to version 6.0.)
+%
+% The author--year information is transferred from the \btx{} database to
+% the document via |\bibitem| commands in the |thebibliography|
+% environment. Standard \LaTeX\ simply assigns a running number to these
+% entries, and writes that number with the citation key to the auxiliary
+% file. For author--year citations, the author list and year must be written
+% somehow to the auxiliary file. The form for this is to be
+% \begin{quote}
+% |\bibcite|\marg{key}|{|\marg{num}\marg{year}\marg{short}\marg{long}|}|
+% \end{quote}
+% This is the same form as in standard \LaTeX, except that the second
+% argument becomes a set of 4 items. Here \emph{num} is the sequential
+% number that is to be used if a numerical style is selected, \emph{short}
+% is the abbreviate author list (Jones et al.), \emph{long} the full author
+% list.
+%
+% The author--year information is contained in the optional argument to
+% |\bibitem|, but just how it is formatted depends on the system used. The
+% native \thestyle\ syntax is
+% \begin{quote}
+% |\bibitem[|\emph{short}|(|\emph{year}|)|\emph{long}|]|\marg{key}
+% \end{quote}
+% while the \texttt{chicago} system is
+% \begin{quote}
+% |\bibitem[\protect\citeauthoryear|\marg{long}\marg{short}\marg{year}|]|%
+% \marg{key}
+% \end{quote}
+%
+% \begin{macro}{\NAT@ifcmd}
+% \changes{6.0}{1995 Sep 4}{Add macro}
+% \begin{macro}{\NAT@ifxcmd}
+% \changes{6.0}{1995 Sep 4}{Add macro}
+% It is necessary to process the optional argument by first testing if it
+% contains a command, and if so, to execute that command. Otherwise, insert
+% our own command to process the following text.
+% \begin{macrocode}
+\newcommand\NAT@ifcmd{\futurelet\NAT@temp\NAT@ifxcmd}
+\newcommand\NAT@ifxcmd{\ifx\NAT@temp\relax\else\expandafter\NAT@bare\fi}
+% \end{macrocode}
+% This actually only tests if the next token expands to |\relax|, which is
+% what |\protect| will be at this point. If so, just procede: the command
+% itself follows. Otherwise, insert |\NAT@bare|. (Note, we must also define
+% the possible commands like |\citeauthoryear| to do what we want.)
+% \end{macro}\end{macro}
+%
+% \begin{macro}{\NAT@bare}
+% \changes{6.0}{1995 Sep 4}{Add macro}
+% \changes{6.6}{1997 Jun 4}{The \cs{stepcounter} made always present}
+% The command that is inserted if none is present must parse the native
+% syntax for the author--year information. The template is somewhat complex
+% because it must be able to test if there are no parentheses at all, in
+% which case it activates the alternative, |\NAT@apalk| for the
+% \texttt{apalike} syntax. When |\NAT@ifcmd| is invoked, it adds
+% |(@)(@)\@nil| in order to provide the full template of |\NAT@bare|; if the
+% argument itself contains no text in parentheses (not \thestyle{}
+% syntax) then |#2| will be |@|; otherwise, |#4| catches the extra
+% parentheses.
+%
+% Using |(@)| instead of the earlier |()| (pre~7.0) allows empty years to be
+% given. Empty years are now permitted for citations with a code designation
+% in place of the authors. Troubles will now occur if the year begins with
+% |@|.
+% \begin{macrocode}
+\def\NAT@bare#1(#2)#3(@)#4\@nil#5{%
+%<*all|apalike|authordate>
+ \if @#2
+ \expandafter\NAT@apalk#1, , \@nil{#5}\else
+%</all|apalike|authordate>
+ \stepcounter{NAT@ctr}%
+ \NAT@wrout{\arabic {NAT@ctr}}{#2}{#1}{#3}{#5}
+%<all|apalike|authordate>\fi
+}
+% \end{macrocode}
+% The |NAT@ctr| above contains the designation of whatever counter is
+% selected in the list environment for the \texttt{thebibliography}; it is
+% the sequential counter for the entries.
+% \end{macro}
+%
+% \begin{macro}{\NAT@wrout}
+% \changes{6.0}{1995 Sep 4}{Add macro}
+% \begin{macro}{\NAT@noname}
+% \changes{6.0}{1995 Sep 6}{Add macro}
+% \changes{6.0}{1995 Sep 21}{Prevent expansion of forced space (tilde)}
+% Write the information to the auxiliary file as two arguments to |\bibcite|.
+%
+% Note: the 5 arguments are: counter, year, short list, long list, key.
+% The two author lists are written enclosed in braces to make sure any
+% font commands are kept local. Otherwise, one level of braces disappears for
+% authors like |{\em Jones}|.
+%
+% To test later for the absence of names, define |\NAT@noname| here.
+% Define it with |\def|, otherwise it will be `long' and will not test
+% correctly with |\NAT@all@names| which is defined with |\gdef|.
+% \begin{macrocode}
+\newcommand\NAT@wrout[5]{%
+\if@filesw
+ {\let\protect\noexpand\let~\relax
+ \immediate
+ \write\@auxout{\string\bibcite{#5}{{#1}{#2}{{#3}}{{#4}}}}}\fi
+\ignorespaces}
+\def\NAT@noname{{}}
+% \end{macrocode}
+% \end{macro}\end{macro}
+%
+% \begin{macro}{\bibitem}
+% \changes{6.0}{1995 Sep 4}{Recode from standard}
+% \begin{macro}{\@lbibitem}
+% \changes{6.0}{1995 Sep 4}{Recode from standard}
+% \changes{6.4}{1996 Oct 2}{Add dummy macros for \texttt{hyperref.sty}}
+% The above commands are initiated with |\NAT@ifcmd| which decides whether
+% |\NAT@bare| or one of the other commands is to be executed on the
+% following arguments. It is actually |\@lbibitem| that calls |\NAT@ifcmd|,
+% which in turn is invoked by the user command |\bibitem|.
+%
+% If |\bibitem| has no optional argument, then we have a numerical citation
+% style, which is to be forced by setting |\NAT@stdbst|. Put the sequential
+% counter value in as the argument to |\@lbibitem| which is then treated as
+% a non-author--year label.
+% \begin{macrocode}
+\renewcommand\bibitem{%
+ \@ifnextchar[{\@lbibitem}{%
+%<!subpack> \global\NAT@stdbsttrue
+ \stepcounter{NAT@ctr}\@lbibitem[\arabic{NAT@ctr}]}}
+% \end{macrocode}
+% Write the label with |\item| in the bibliography listing with the current
+% value of |\NAT@num|, if it exists. This will either be the sequential
+% number or whatever non-author--year text that was given as a special
+% `numerical'. Since |\@biblabel| outputs only in numerical mode, this
+% label vanishes for author--year mode.
+%
+% Finally invoke |\NAT@ifcmd| with the funny template to activate
+% |\NAT@bare| or some alternative.
+%
+% \changes{6.8b}{1998 July 6}{To work with \texttt{chapterbib} and
+% \texttt{backref}}
+% The \texttt{hyperref} package can call the \texttt{backref} package which
+% do not work with the \texttt{chapterbib} package. I have arranged with
+% Sebastian Rahtz to add the compatibility via \thestyle. Thus I add a fix to
+% include the |\@extra@b@citeb| suffix to the |\br@#2| commands called by
+% \texttt{backref}.
+% \begin{macrocode}
+\def\@lbibitem[#1]#2{%
+ \if\relax\@extra@b@citeb\relax\else
+ \@ifundefined{br@#2\@extra@b@citeb}{}{%
+ \@namedef{br@#2}{\@nameuse{br@#2\@extra@b@citeb}}}\fi
+ \@ifundefined{b@#2\@extra@b@citeb}{\def\NAT@num{}}{\NAT@parse{#2}}%
+ \item[\hfil\hyper@natanchorstart{#2\@extra@b@citeb}\@biblabel{\NAT@num}%
+ \hyper@natanchorend]%
+ \NAT@ifcmd#1(@)(@)\@nil{#2}}
+% \end{macrocode}
+% Note: in standard \LaTeX, the sequential list counter is printed directly
+% with |\item|, and then written to the auxiliary file so that |\cite| can
+% refer to it on the next run. Here, |\item| prints exactly the same thing
+% as |\cite| on the current run, if we are in numerical mode, otherwise
+% nothing.
+%
+% \changes{6.3}{1996 Jun 10}{Include \texttt{showkeys} coding if already
+% loaded}
+% \changes{6.4}{1996 Jun 27}{Remove from 2.09 coding}
+% \changes{6.7}{1997 Sep 12}{Test for existence of \cs{SK@lbibitem}}
+% If the \texttt{showkeys} package has already been loaded, the revised
+% version of |\@lbibitem| will not have been saved. In this case, rerun some
+% of the coding from that package. (If \texttt{showkeys} is loaded after
+% \thestyle, there is no problem.)
+%
+% Do not test if \texttt{showkeys} is loaded, but rather if |\SK@lbibitem|
+% is defined. See comment on \texttt{showkeys} with option \texttt{final}
+% on page~\pageref{SKdef}.
+%
+% \begin{macrocode}
+%<*!209>
+\ifx\SK@lbibitem\@undefined\else
+ \let\SK@lbibitem\@lbibitem
+ \def\@lbibitem[#1]#2{%
+ \SK@lbibitem[#1]{#2}\SK@\SK@@label{#2}\ignorespaces}\fi
+%</!209>
+% \end{macrocode}
+% \end{macro}\end{macro}
+%
+% \begin{macro}{\ifNAT@stdbst}
+% \changes{6.0}{1995 Sep 4}{Add flag}
+% If any non-author--year |\bibitem|s have been issued, then force
+% numerical mode, since the author--year |\bibitem|s can handle this, but
+% the numerical ones cannot work in author--year mode. Do this by inserting
+% |\NAT@numberstrue| in the auxiliary file.
+% \begin{macrocode}
+%<*!subpack>
+\newif\ifNAT@stdbst \NAT@stdbstfalse
+
+%<209>\let\NAT@enddoc=\enddocument
+%<209>\def\enddocument
+%<!209>\AtEndDocument
+ {\ifNAT@stdbst\if@filesw\immediate\write\@auxout{\string
+ \global\string\NAT@numberstrue}\fi\fi
+%<209>\NAT@enddoc
+ }
+%</!subpack>
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\bibcite}
+% \changes{6.1}{1995 Dec 5}{Add own coding for this macro}
+% \changes{6.1a}{1995 Dec 19}{Add own test for changed citations}
+% Not wanting to rely on the coding for |\bibcite| in the kernel, I define
+% it myself. It is not enough just to `provide' it, for it must do the
+% right thing: write a label named |\b@|\emph{key}. The \LaTeX3 boys
+% might decide to keep the command, but have it store the citations with
+% a different prefix.
+%
+% (I outsmarted myself here again. The test for changed citations and
+% references involves reading in the auxiliary file with revised
+% definitions for |\label| and |\bibcite|. The December~1995 release does
+% this via a generalized labelling command |\@newl@bel|. As a result, I
+% must add this test myself. Not so bad, because the warning comes from
+% \thestyle\ and explicitly refers to citations instead of just
+% `references'.)
+% \begin{macrocode}
+%<*!209>
+\providecommand\bibcite{}
+\renewcommand\bibcite[2]{\@ifundefined{b@#1\@extra@binfo}\relax
+ {\NAT@citemultiple
+ \PackageWarningNoLine{natbib}{Citation `#1' multiply defined}}%
+ \global\@namedef{b@#1\@extra@binfo}{#2}}
+\AtEndDocument{\NAT@swatrue\let\bibcite\NAT@testdef}
+\newcommand\NAT@testdef[2]{%
+ \def\NAT@temp{#2}\expandafter \ifx \csname b@#1\@extra@binfo\endcsname
+ \NAT@temp \else \ifNAT@swa \NAT@swafalse
+ \PackageWarningNoLine{natbib}{Citation(s) may have
+ changed.\MessageBreak
+ Rerun to get citations correct}\fi\fi}
+%</!209>
+%<209>\renewcommand\bibcite[2]{\global\@namedef{b@#1\@extra@binfo}{#2}}
+% \end{macrocode}
+% \end{macro}
+%
+% \subsection{Other Author--Year Schemes}
+% \begin{macro}{\NAT@apalk}
+% \changes{4.1}{1993 Oct 4}{Simplify by using comma-space as separator}
+% \changes{5.3}{1994 Sep 13}{Full author list equals short list}
+% \changes{5.5}{1995 May 18}{Renamed from \cs{@citeapalk}}
+% \changes{6.0}{1995 Sep 4}{Recoded for version~6.0}
+% If the argument of |\bibitem| contains no command, and if it does not
+% conform to the \thestyle{} syntax, then try the \texttt{apalike}
+% syntax (\emph{short}\texttt{, }\emph{year}). This has a funny template
+% too in order to test for different syntax, which is indicated when |#2|
+% is empty. In this case, give up trying to fit it to author--year formats,
+% and go over to `numerical' with a special label. Set the flag
+% |\NAT@stdbst| to mark this. This forces a numerical citation style.
+% \begin{macrocode}
+%<*all|apalike|authordate>
+\newcommand\NAT@apalk{}
+\def\NAT@apalk#1, #2, #3\@nil#4{\if\relax#2\relax
+%<!subpack> \global\NAT@stdbsttrue
+ \NAT@wrout{#1}{}{}{}{#4}\else
+ \stepcounter{NAT@ctr}%
+ \NAT@wrout{\arabic {NAT@ctr}}{#2}{#1}{}{#4}\fi}
+%</all|apalike|authordate>
+% \end{macrocode}
+% Note: the |NAT@ctr| is stepped here and everywhere else it is used,
+% except when a special `numerical' label is being used. This conforms to
+% standard \LaTeX\ which only increments the counter for pure numerical
+% labels, without an optional argument to |\bibitem|.
+% \end{macro}
+%
+% The other schemes of citation labelling may also be accommodated, more
+% easily than \texttt{apalike}. It is just necessary to define the particular
+% commands, like |\citeauthoryear| to write the arguments to the
+% auxiliary file in the required. These commands are detected by
+% |\NAT@ifcmd| and simply left to be executed.
+%
+% The only complication is that |\citeauthoryear| may be given with two or
+% three arguments. This is accommodated by testing the |#3| and changing
+% the form of the write command accordingly.
+%
+% The form of the template is the same as for |\NAT@bare|, since this
+% command is inserted in its place and must therefore conform to its
+% syntax.
+%
+% \begin{macro}{\citeauthoryear}
+% \changes{5.3}{1994 Sep 13}{Allow full authors in citation}
+% \changes{6.0}{1995 Sep 4}{Recode for version 6.0}
+% For \texttt{newapa.bst} itself, the commands |\citestarts|, |\citeends|,
+% as well as |\betweenauthors| must be defined; for others in this group,
+% these commands are not needed.
+% \begin{macrocode}
+%<*newapa|chicago|all>
+\newcommand\citeauthoryear{}
+\def\citeauthoryear#1#2#3(@)(@)\@nil#4{\stepcounter{NAT@ctr}\if\relax#3\relax
+ \NAT@wrout{\arabic {NAT@ctr}}{#2}{#1}{}{#4}\else
+ \NAT@wrout{\arabic {NAT@ctr}}{#3}{#2}{#1}{#4}\fi}
+\newcommand\citestarts{\NAT@open}
+\newcommand\citeends{\NAT@close}
+\newcommand\betweenauthors{and}
+%</newapa|chicago|all>
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\astroncite}
+% \changes{6.0}{1995 Sep 4}{Recode for version 6.0}
+% The |\astroncite| command must similarly conform to |\NAT@bare| syntax
+% and put its arguments into the auxiliary file in the correct order.
+% \begin{macrocode}
+%<*astron|all>
+\newcommand\astroncite{}
+\def\astroncite#1#2(@)(@)\@nil#3{\stepcounter{NAT@ctr}\NAT@wrout{\arabic
+{NAT@ctr}}{#2}{#1}{}{#3}}
+%</astron|all>
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\citename}
+% \changes{6.0}{1995 Sep 4}{Recode for version 6.0}
+% The |\citename| command just converts its arguments to the |\NAT@apalk|
+% syntax, since its first argument should end in \verb*!, ! as for
+% \texttt{apalike}. By making use of |\NAT@apalk| here, it is also possible
+% to check for non-conformity of the syntax.
+% \begin{macrocode}
+%<*authordate|all>
+\newcommand\citename{}
+\def\citename#1#2(@)(@)\@nil#3{\expandafter\NAT@apalk#1#2, \@nil{#3}}
+%</authordate|all>
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\harvarditem}
+% \changes{5.3}{1994 Sep 13}{Allow full authors in citation}
+% \changes{5.5}{1995 May 18}{Defined in \LaTeXe\ terms}
+% The Harvard family is allowed for simply by defining |\harvarditem| in
+% terms of |\bibitem| with the \thestyle{} form.
+%
+% The |\harvarditem| must allow for the optional argument, which is
+% the short author list. Use the short list in |\bibitem| if it is there,
+% otherwise the long list must be taken.
+%
+% \begin{macrocode}
+%<*harvard|all>
+%<!209>\newcommand\harvarditem[4][]%
+%<209>\def\harvarditem{\@ifnextchar[{\@harvarditem}{\@harvarditem[]}}
+%<209>\def\@harvarditem[#1]#2#3#4%
+ {\if\relax#1\relax\bibitem[#2(#3)]{#4}\else
+ \bibitem[#1(#3)#2]{#4}\fi }
+% \end{macrocode}
+% The command |\citeasnoun| must be defined since \texttt{harvard.bst}
+% can add it for cross-referencing.
+% \end{macro}
+%
+% \begin{macro}{\harvardleft}
+% \changes{5.3}{1994 Sep 13}{Add macro}
+% \begin{macro}{\harvardright}
+% \changes{5.3}{1994 Sep 13}{Add macro}
+% \begin{macro}{\harvardyearleft}
+% \changes{5.3}{1994 Sep 13}{Add macro}
+% \begin{macro}{\harvardyearright}
+% \changes{5.3}{1994 Sep 13}{Add macro}
+% \begin{macro}{\harvardand}
+% \changes{5.3}{1994 Sep 13}{Add macro}
+% \begin{macro}{\harvardurl}
+% \changes{5.3}{1994 Sep 13}{Add macro}
+% \changes{6.7}{1997 Jul 15}{Fix macro, use only one \texttt{\#}}
+% The \texttt{harvard} package has been updated for \LaTeXe, and includes
+% some new punctuation commands in the accompanying \texttt{bst} files.
+% (Maybe they were always there and I overlooked them.) In order for
+% \thestyle{} to work with these, it needs to define them. The |left| and
+% |right| commands have equivalents already; |\harvardurl| is defined
+% as in \texttt{harvard.sty}. It is necessary to define |\harvardand|
+% conditionally, and only later, in case it has already been set to
+% something else by a |\bibstyle@xxx| (e.g., \texttt{agsm} sets it
+% to |\&|.)
+% \begin{macrocode}
+\newcommand\harvardleft{\NAT@open}
+\newcommand\harvardright{\NAT@close}
+\newcommand\harvardyearleft{\NAT@open}
+\newcommand\harvardyearright{\NAT@close}
+%<!209>\AtBeginDocument{\providecommand{\harvardand}{and}}
+%<209>\def\harvardand{and}
+\newcommand\harvardurl[1]{\textbf{URL:} \textit{#1}}
+%</harvard|all>
+% \end{macrocode}
+% \end{macro}\end{macro}\end{macro}\end{macro}\end{macro}\end{macro}
+%
+% \subsection{The Bibliography Listing}
+% Changes must be made to the \texttt{thebibliography} environment for
+% author--year citations. This is done be defining the environment with the
+% features common to both schemes, and then by invoking |\@bibsetup|, which
+% is either the author--year or numerical version.
+%
+% \begin{macro}{\bibsection}
+% \changes{4.2}{1993 Oct 22}{Make specific for JGR, GRL, NLINPROC}
+% \changes{5.5}{1995 May 18}{Use \cs{renewcommand}}
+% \changes{6.2}{1996 Apr 15}{Modified for \texttt{amsart} and \texttt{amsbook}}
+% \changes{6.4}{1996 Sep 1}{Modified for \texttt{sectionbib} option}
+% \changes{6.5}{1997 Feb 5}{Allow for \cs{bib@headings} in KOMA scripts}
+% \changes{7.0}{1999 May 21}{Use \cs{chapter*} for \texttt{amsbook}}
+% First, |\bibsection| is defined according to the main style: if chapters
+% exist, then the bibliography is a numberless chapter, otherwise a
+% numberless section. For the specific journals, |\bibsection| takes on
+% special definitions.
+%
+% Since the AMS classes \texttt{amsart} and \texttt{amsbook} redefine
+% |\section*| in a way that is incompatible with the way it is used in
+% the \texttt{bibliographystyle} environment, it is necessary to remove the
+% |\@mkboth| from the section title. Since these classes do not use this
+% command at this point, there is no loss of functionality.
+%
+% The packages of the KOMA scripts make use of |\bib@heading| which functions
+% much like |\bibsection|. If it is defined, let |\bibsection| be equal to it.
+% \begin{macrocode}
+%<*!agu&!egs>
+%<!209>\providecommand\bibsection{}
+%<209>\def\bibsection{}
+\@ifundefined{chapter}%
+ {\renewcommand\bibsection{\section*{\refname
+ \@mkboth{\MakeUppercase{\refname}}{\MakeUppercase{\refname}}}}}
+ {\@ifundefined{NAT@sectionbib}%
+ {\renewcommand\bibsection{\chapter*{\bibname
+ \@mkboth{\MakeUppercase{\bibname}}{\MakeUppercase{\bibname}}}}}
+ {\renewcommand\bibsection{\section*{\bibname
+ \ifx\@mkboth\@gobbletwo\else\markright{\MakeUppercase{\bibname}}\fi}}}}
+%<*!subpack>
+%<*!209>
+\@ifclassloaded{amsart}%
+ {\renewcommand\bibsection{\section*{\refname}}}{}
+\@ifclassloaded{amsbook}%
+ {\renewcommand\bibsection{\chapter*{\bibname}}}{}
+%</!209>
+\@ifundefined{bib@heading}{}{\let\bibsection\bib@heading}
+%</!subpack>
+%</!agu&!egs>
+%<egs>\def\bibsection{\if@draft\newpage\fi
+%<egs> \noappendix\section*{\refname}}
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{environment}{thebibliography}
+% \changes{4.1b}{1993 Oct 18}{Add \cmd{\bibfont}, defaulted
+% to \cmd{\relax}}
+% \changes{4.2}{1993 Oct 22}{Add coding for JGR, GRL, NLINPROC}
+% \changes{4.2}{1993 Nov 20}{Remove coding for AGU, since AGU-supplied
+% coding is adequate but different}
+% \changes{5.1}{1994 Jun 22}{Put \cmd{\bibfont} at start so \cmd{\list}
+% uses list parameters appropriate for the font size}
+% \changes{5.1}{1994 Jun 22}{Add \cmd{\if@openbib} as in \LaTeXe}
+% \changes{5.5}{1995 Mar 27}{Add special cross-ref citations for compatibility
+% with \texttt{harvard}, \texttt{chicago}, and \texttt{named}}
+% \changes{6.1}{1995 Nov 22}{Replace \cs{if@openbib} with \cs{ifNAT@openbib}}
+% \changes{6.1}{1995 Dec 4}{Replace counter \texttt{enumiv} with
+% \texttt{NAT@ctr} and refer to it explicitly, not with \cs{@listctr}}
+% \changes{6.1}{1995 Dec 4}{Use \cs{PackageWarning} for empty
+% bibliography}
+% \changes{6.9a}{1999 Apr 20}{Add \cs{bibpreamble}}
+%
+% The \texttt{thebibliography} environment is defined much as normal, except
+% that |\bibsetup| contains the special features for numerical or
+% author--year styles. The command |\bibfont| permits permits different
+% font sizes or styles to be used in the list. For example, for
+% \textsl{Nonlinear Processes} it is |\small|. This means |\bibfont| must
+% be issued before the |\list| command, since the list parameters depend
+% on the current font size. For \textsl{AGU}, the whole
+% |\thebibliography| is left off, since the AGU-supplied coding will
+% do. It is only necessary to add |\noappendix| to the AGU coding.
+%
+% I have replaced |\if@openbib| with |\ifNAT@openbib| in order to be
+% independent of the standard classes; this flag disappeared with the
+% December~1995 release of \LaTeX, so I do it myself just to be sure.
+%
+% At the same time,
+% I have also decided to use my own counter |NAT@ctr| for the numericals;
+% previously I used |enumiv| as in the standard, and refered to it
+% elsewhere with |\@listctr|, but now I refer to it explicitly. This is to
+% avoid trouble if |\@listctr| should ever disappear. (The value of
+% |\@listctr| is set by |\usecounter|.)
+% \begin{macrocode}
+\newcounter{NAT@ctr}
+%<*!agu>
+\renewenvironment{thebibliography}[1]{%
+ \bibsection\parindent \z@\bibpreamble\bibfont\list
+ {\@biblabel{\arabic{NAT@ctr}}}{\@bibsetup{#1}%
+ \setcounter{NAT@ctr}{0}}%
+%<*!209&!subpack>
+ \ifNAT@openbib
+ \renewcommand\newblock{\par}
+ \else
+ \renewcommand\newblock{\hskip .11em \@plus.33em \@minus.07em}%
+ \fi
+%</!209&!subpack>
+%<209|subpack> \def\newblock{\hskip .11em plus.33em minus.07em}%
+ \sloppy\clubpenalty4000\widowpenalty4000
+ \sfcode`\.=1000\relax
+% \end{macrocode}
+% The files \texttt{chicago.bst} and \texttt{named.bst} can add the
+% commands |\citeN| and |\shortcite| respectively to the \texttt{.bbl}
+% files, for cross-referencing. Similarly, \texttt{harvard.bst} can add
+% |\citeasnoun|. These commands must therefore be accommodated,
+% as least within the |thebibliography| environment.
+% \begin{macrocode}
+%<newapa|chicago|all> \let\citeN\cite \let\shortcite\cite
+%<harvard|all> \let\citeasnoun\cite
+ }{\def\@noitemerr{%
+%<209> \@warning
+%<!209> \PackageWarning{natbib}
+ {Empty `thebibliography' environment}}%
+ \endlist\vskip-\lastskip}
+%<!egs>\let\bibfont\relax
+%<egs>\let\bibfont\small
+\let\bibpreamble\relax
+%</!agu>
+%<*agu>
+\let\aguthebib=\thebibliography
+\def\thebibliography#1{\noappendix\aguthebib{#1}}
+%</agu>
+% \end{macrocode}
+% \end{environment}
+%
+% \subsection{Compatibility Commands}
+% \begin{macro}{\reset@font}
+% \begin{macro}{\refname}
+% \changes{6.4}{1996 Jun 18}{Provide name with \LaTeXe\ too}
+% \begin{macro}{\bibname}
+% \changes{6.4}{1996 Jun 18}{Provide name with \LaTeXe\ too}
+% For older implementations of \LaTeX~2.09 (before December, 1991) the
+% |\reset@font| command does not exist. It is defined to be |\relax| under
+% normal \LaTeX{}, but does more under NFSS. In case it is not defined, add
+% it here. The naming commands |\bibname| and |\refname| are similarly
+% unknown for this old \LaTeX. They are sometimes even unknown in non-standard
+% classes that are used in place of \texttt{article}, \texttt{report}, and
+% \texttt{book}.
+% \begin{macrocode}
+%<*!209>
+\providecommand\reset@font{\relax}
+\providecommand\bibname{Bibliography}
+\providecommand\refname{References}
+%</!209>
+%<*209>
+\@ifundefined{reset@font}{\let\reset@font=\relax}{}
+%<!agu&!egs>\@ifundefined{bibname}{\newcommand\bibname{Bibliography}}{}
+\@ifundefined{refname}{\newcommand\refname{References}}{}
+%</209>
+% \end{macrocode}
+% \end{macro}\end{macro}\end{macro}
+%
+% \begin{macro}{\NAT@citeundefined}
+% \changes{6.1}{1995 Nov 22}{Add macro}
+% The December~1995 release of \LaTeX\ considered renaming the command
+% |\G@refundefinedtrue| for flagging undefined references. However, since a
+% number of packages, including \thestyle, were affected, it was decided to
+% retain the old name for the new coding. I had already decided to go for
+% an independent coding, which does exactly the same thing.
+% \begin{macrocode}
+%<*!209>
+\newcommand\NAT@citeundefined{\gdef \NAT@undefined {%
+ \PackageWarningNoLine{natbib}{There were undefined citations}}}
+\let \NAT@undefined \relax
+% \end{macrocode}
+% \end{macro}
+% \begin{macro}{\NAT@citemultiple}
+% \changes{6.1}{1995 Dec 6}{Add macro}
+% Add the warning about multiply-defined citations, as part of the
+% do-it-yourself |\bibcite| definition.
+% \begin{macrocode}
+\newcommand\NAT@citemultiple{\gdef \NAT@multiple {%
+ \PackageWarningNoLine{natbib}{There were multiply defined citations}}}
+\let \NAT@multiple \relax
+\AtEndDocument{\NAT@undefined\NAT@multiple}
+%</!209>
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@mkboth}
+% \changes{6.1}{1995 Dec 4}{Provide macro in case it is removed from
+% kernel}
+% Having been burned by the December~1995 update on several internal
+% commands, I have decided to make \thestyle\ as independent as
+% possible, or at least to avoid it crashing when internals are changed or
+% disappear in future. The |\@mkboth| is used in the bibliography listing,
+% and is the same as |\makeboth| with \texttt{headings} pagestyle. Provide
+% a dummy in case it disappears. If the kernel should use a different
+% command in future, the headings will not function, but at least there
+% will be no crash. (Also needed for very old versions of \LaTeX~2.09.)
+% \begin{macrocode}
+%<209>\@ifundefined{@mkboth}{\newcommand\@markboth[2]{}}{}
+%<!209>\providecommand\@mkboth[2]{}
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\MakeUppercase}
+% \changes{6.1}{1995 Dec 4}{Provide compatibility for older versions}
+% The |\MakeUppercase| command replaces |\uppercase| in \LaTeXe\ of
+% June~1995. Provide it for earlier versions.
+% \begin{macrocode}
+%<209>\let\MakeUppercase\uppercase
+%<!209>\providecommand\MakeUppercase{\uppercase}
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@extra@b@citeb}
+% \changes{6.4}{1996 Sep 1}{Add macro for \texttt{chapterbib.sty}}
+% \begin{macro}{\@extra@binfo}
+% \changes{6.4}{1996 Sep 1}{Add macro for \texttt{chapterbib.sty}}
+% Two commands used by the \texttt{chapterbib} package, but which must
+% be defined to be nothing for use without that package. Do not |\let| them
+% be |\relax|, for that package checks if they exist (i.e., not |\relax|)
+% and redefines things like |\@citex|, which we do not want to have happen.
+% The necessary redefinitions are already included in \thestyle.
+% \begin{macrocode}
+%<209>\@ifundefined{@extra@b@citeb}{\def\@extra@b@citeb{}}{}
+%<!209>\providecommand{\@extra@b@citeb}{}
+\gdef\@extra@binfo{}
+% \end{macrocode}
+% \end{macro}\end{macro}
+%
+% \begin{macro}{\hyper@natanchorstart}
+% \changes{6.4}{1996 Oct 2}{Provide macro for \texttt{hyperref} package}
+% \begin{macro}{\hyper@natanchorend}
+% \changes{6.4}{1996 Oct 2}{Provide macro for \texttt{hyperref} package}
+% \begin{macro}{\hyper@natlinkstart}
+% \changes{6.4}{1996 Oct 2}{Provide macro for \texttt{hyperref} package}
+% \begin{macro}{\hyper@natlinkend}
+% \changes{6.4}{1996 Oct 2}{Provide macro for \texttt{hyperref} package}
+% \begin{macro}{\hyper@natlinkbreak}
+% \changes{6.8b}{1998 July 2}{Provide macro for \texttt{hyperref} package}
+% The \texttt{hyperref} package of Sebastian Rahtz and Yannis Haralambous
+% defines these macros to
+% make hypertext links and references. Without that package, these macros
+% must be turned off. The order of loading \thestyle\ and \texttt{hyperref}
+% should not be important even though it is recommended that
+% \texttt{hyperref} be loaded last.
+%
+% The \texttt{hyperref} package does not work with \texttt{chapterbib}, but I
+% have arranged with Sebastian Rahtz to add the necessary suffixes via
+% \thestyle. This involves adding |\@extra@b@citeb| to all calls to
+% |\hyper@natlinkstart| and |\hyper@natanchorstart|. To get \texttt{backref} to
+% work, I needed to add a hack to my |\@lbibitem|.
+%
+% The |\hyper@natlinkbreak| to designed to break links between the names and
+% date, avoiding some possible problems when links go over a page.
+% \begin{macrocode}
+%<*!209>
+\providecommand\hyper@natanchorstart[1]{}
+\providecommand\hyper@natanchorend{}
+\providecommand\hyper@natlinkstart[1]{}
+\providecommand\hyper@natlinkend{}
+\providecommand\hyper@natlinkbreak[2]{#1}
+%</!209>
+%<*209>
+\@ifundefined{hyper@natanchorstart}{\def\hyper@natanchorstart#1{}}{}
+\@ifundefined{hyper@natanchorend}{\def\hyper@natanchorend{}}{}
+\@ifundefined{hyper@natlinkstart}{\def\hyper@natlinkstart#1{}}{}
+\@ifundefined{hyper@natlinkend}{\def\hyper@natlinkend{}}{}
+\@ifundefined{hyper@natlinkbreak}{\def\hyper@natlinkbreak#1#2{#1}}{}
+%</209>
+% \end{macrocode}
+% \end{macro}\end{macro}\end{macro}\end{macro}\end{macro}
+%
+% \changes{6.7}{1997 Nov 10}{Accommodate \texttt{babel}'s redefinitions}
+% \changes{6.9}{1999 Feb 26}{Include \texttt{babel} accommodation with
+% \texttt{subpack}}
+% \changes{6.9a}{1999 Apr 20}{Fixes for \texttt{babel} 3.6t}
+% The \texttt{babel} bundle redefines several internal commands in order to
+% handle special active characters required by some languages. One of these
+% redefined commands is |\@citex|. This fails for \thestyle\ for two
+% reasons: the syntax is different and the \thestyle\ definition of |\@citex|
+% has not yet been finalized. I correct this doing \texttt{babel}'s
+% redefinition at the |\begin{document}| with the right syntax.
+%
+% The main purpose of these redefinitions is to allow special active characters
+% to appear in the citation keys. To this end, |\@citex|, |\bibcite|,
+% |\nocite|, |\@bibitem|, and |\@lbibitem| need changing such that the active
+% characters are turned off when the keys are processed. In the case of
+% |\bibcite|, which is only ever called in a context where the active
+% characters are turned off, the second argument, the actual label, has the
+% active characters temporarily turned on. This causes \thestyle\ to crash;
+% hence \texttt{babel} now checks (v3.6t) for \thestyle\ and keeps the original
+% definition. This means any active characters in the \thestyle\ labels will
+% not be processed correctly, but these special characters should never be here
+% anyway, since they violate portability.
+%
+% It is also necessary to redefine |\NAT@testdef| which also uses the keys as
+% arguments. (It is a replacement for |\bibcite| for when the \texttt{.aux}
+% file is read in at the end.) Furthermore, |\@lbibitem| needs redefining, but
+% \texttt{babel} does not (yet) do this, only |\@bibitem|.
+%
+% Strictly speaking, \thestyle\ should be loaded before \texttt{babel} so that
+% the latter saves and modifies the \thestyle\ definitions, and not the
+% standard \LaTeX\ ones. However, in reality this is not necessary since
+% |\bibcite| is not redefined with \thestyle\ and |\@citex| is redefined by
+% \thestyle\ itself after the preamble. However, |\nocite| and |\@lbibitem| can
+% cause problems with the ordering. Solve this by redefining them immediately
+% if \texttt{babel} is present (i.e., \texttt{babel} before \thestyle); in this
+% case, \texttt{babel} has previously redefined them wrongly, \thestyle\ then
+% creates its own base definitions, and the \texttt{babel} redefinition is now
+% carried out again, with the proper ``originals''. A complication comes with
+% |\@lbibitem| in that at present \texttt{babel} does not redefine it, so it
+% must be (conditionally) added to the |\AtBeginDocument| hook in case
+% \thestyle\ is loaded first. If \texttt{babel} is changed in future, this
+% addition will not be needed and will not be executed. Thus the order of the
+% two packages is unimportant.
+%
+% Note: all this redefining is only important if there are keys containing
+% active characters. One point to note is that optional notes containing active
+% characters will not work right for \texttt{babel}, neither with or
+% without \thestyle. They will work with the \texttt{german} package, but then
+% the keys with active characters will not. Oh boy!
+%
+% With the journal coding (\texttt{subpack}), things are slightly different.
+% For them it is |\@citex| that is defined directly, not |\NAT@citex|, so
+% I have to restore that definition which \texttt{babel} has already
+% altered and stored in |\org@@citex|.
+%
+% \begin{macrocode}
+%<*!209>
+%<*!subpack>
+\@ifundefined{bbl@redefine}{}{%
+ \bbl@redefine\nocite#1{%
+ \@safe@activestrue\org@nocite{#1}\@safe@activesfalse}%
+\bbl@redefine\@lbibitem[#1]#2{%
+ \@safe@activestrue\org@@lbibitem[#1]{#2}\@safe@activesfalse}%
+}
+%</!subpack>
+\AtBeginDocument{\@ifundefined{bbl@redefine}{}{%
+%<subpack>\let\@citex\org@@citex
+\bbl@redefine\@citex[#1][#2]#3{%
+ \@safe@activestrue\org@@citex[#1][#2]{#3}\@safe@activesfalse}%
+\bbl@redefine\NAT@testdef#1#2{%
+ \@safe@activestrue\org@NAT@testdef{#1}{#2}\@safe@activesfalse}%
+\@ifundefined{org@@lbibitem}{%
+\bbl@redefine\@lbibitem[#1]#2{%
+ \@safe@activestrue\org@@lbibitem[#1]{#2}\@safe@activesfalse}}{}%
+}}
+%</!209>
+% \end{macrocode}
+%
+% \subsection{Sorting and Compression of Numbers}
+% The \texttt{cite} and (obsolete) \texttt{citesort} packages by Donald
+% Arseneau provide the coding for printing multiple citation numbers in
+% ascending order, and with a range where applicable. That is, if the
+% normal result of |\cite{..}| with several keys were [5, 3, 8, 4], the new
+% result would be [3--5, 8].
+%
+% Since \texttt{cite.sty} totally reimplements the citation commands (as
+% does \thestyle) it is not possible to make the two compatible. Instead, I
+% have removed the necessary coding from \texttt{cite.sty}, converted it to
+% \thestyle\ format, and added it here.
+%
+% Originally I borrowed the coding from the \texttt{cite.sty} package, but for
+% version~6.6, I have adapted the coding so that it orders the citation keys
+% according to the sequence in the reference list. This now works for both
+% numerical and author--year modes. The sorting is activated by the options
+% \texttt{sort} and \texttt{sort\&compress}.
+%
+% \begin{macro}{\NAT@sort@cites}
+% \changes{6.4}{1996 Oct 11}{Add coding from \texttt{cite.sty}}
+% \changes{6.6}{1997 Jun 3}{Redo to sort cite keys; works with author--year
+% mode}
+% This feature is not provided for with \LaTeX~2.09. It does exist in the
+% journal subpackages, being selected by setting |\NAT@sort| accordingly: 0
+% for no sorting; 1 for sorting; 2 for sorting and compression (numerical mode
+% only).
+%
+% The macro |\NAT@sort@cites| places the reordered list of citation keys (the
+% argument to |\cite|\textit{xxx}) in |\NAT@cite@list|. If sorting is turned
+% off, this list is the same as the input.
+%
+% A sorted list of the citation numbers (|\NAT@num@list|) is made up following
+% Arseneau's procedure; from that the citation keys are placed in
+% |\NAT@cite@list| in the same order. If there are any non-numerical values of
+% |\NAT@num|, these are added to |\NAT@nonsort@list|, which is appended at the
+% end to the main list. Finally, the trailing comma is removed with
+% |\NAT@xcom|.
+% \begin{macrocode}
+%<*!209>
+\ifnum\NAT@sort>0
+\newcommand\NAT@sort@cites[1]{%
+\@tempcntb\m@ne
+\let\@celt\delimiter
+\def\NAT@num@list{}%
+\def\NAT@cite@list{}%
+\def\NAT@nonsort@list{}%
+\@for \@citeb:=#1\do{\NAT@make@cite@list}%
+\edef\NAT@cite@list{\NAT@cite@list\NAT@nonsort@list}%
+\edef\NAT@cite@list{\expandafter\NAT@xcom\NAT@cite@list @@}}
+% \end{macrocode}
+% \begin{macro}{\NAT@make@cite@list}
+% This is essentially Arseneau's coding, with some renaming and the addition
+% of |\NAT@cite@list| for the citation keys. The trick with the catcode is
+% his, and it determines if |\NAT@num| is really a number. This is a
+% non-number if the optional argument to |\bibitem| does not conform to any
+% of the allowed \thestyle\ syntaxes, such as if \texttt{alph.bst} is used.
+% \begin{macrocode}
+\begingroup \catcode`\_=8
+\gdef\NAT@make@cite@list{%
+ \edef\@citeb{\expandafter\@firstofone\@citeb}%
+ \@ifundefined{b@\@citeb\@extra@b@citeb}{\def\NAT@num{A}}%
+ {\NAT@parse{\@citeb}}%
+ \ifcat _\ifnum\z@<0\NAT@num _\else A\fi
+ \@tempcnta\NAT@num \relax
+% \end{macrocode}
+% If highest number so far, add at the end.
+% \begin{macrocode}
+ \ifnum \@tempcnta>\@tempcntb
+ \edef\NAT@num@list{\NAT@num@list \@celt{\NAT@num}}%
+ \edef\NAT@cite@list{\NAT@cite@list\@citeb,}%
+ \@tempcntb\@tempcnta
+ \else
+% \end{macrocode}
+% Else, process the numerical list to insert number and citation key.
+% \begin{macrocode}
+ \let\NAT@@cite@list=\NAT@cite@list \def\NAT@cite@list{}%
+ \edef\NAT@num@list{\expandafter\NAT@num@celt \NAT@num@list \@gobble @}%
+ {\let\@celt=\NAT@celt\NAT@num@list}%
+ \fi
+ \else
+% \end{macrocode}
+% If not a number, add it to |\NAT@nonsort@list|.
+% \begin{macrocode}
+ \edef\NAT@nonsort@list{\NAT@nonsort@list\@citeb,}%
+ \fi}
+\endgroup
+% \end{macrocode}
+% \end{macro}
+% This is the macro to insert a new key into the key list. All the keys so
+% far are first stored in |\NAT@@cite@list| and transferred over to
+% |\NAT@cite@list|, with the new key inserted where appropriate. The macros
+% |\NAT@nextc| and |\NAT@restc| return the next entry in the list, or the
+% rest of the list without the first entry, respectively.
+% \begin{macrocode}
+\def\NAT@celt#1{\ifnum #1<\@tempcnta
+ \xdef\NAT@cite@list{\NAT@cite@list\expandafter\NAT@nextc\NAT@@cite@list @@}%
+ \xdef\NAT@@cite@list{\expandafter\NAT@restc\NAT@@cite@list}%
+ \else
+ \xdef\NAT@cite@list{\NAT@cite@list\@citeb,\NAT@@cite@list}\let\@celt\@gobble%
+ \fi}
+\def\NAT@num@celt#1#2{\ifx \@celt #1%
+ \ifnum #2<\@tempcnta
+ \@celt{#2}%
+ \expandafter\expandafter\expandafter\NAT@num@celt
+ \else
+ \@celt{\number\@tempcnta}\@celt{#2}%
+ \fi\fi}
+\def\NAT@nextc#1,#2@@{#1,}
+\def\NAT@restc#1,#2{#2}
+\def\NAT@xcom#1,@@{#1}
+\else
+ \newcommand\NAT@sort@cites[1]{\edef\NAT@cite@list{#1}}\fi
+%</!209>
+% \end{macrocode}
+% \end{macro}
+%
+% \subsection{Local Configuration}
+% \changes{5.2}{1994 Aug 25}{Add reading in of \texttt{natbib.cfg}}
+% \changes{5.5}{1995 Mar 21}{Local configuration read in at end}
+% To accommodate local additional |\bibstyle@| definitions,
+% or any other modifications to the coding, read in
+% configuration file \texttt{natbib.cfg} if it exists.
+% \begin{macrocode}
+%<*!subpack&!209>
+\InputIfFileExists{natbib.cfg}
+ {\typeout{Local config file natbib.cfg used}}{}
+%</!subpack&!209>
+%</package>
+% \end{macrocode}
+%
+% \Finale