path: root/Master/texmf-dist/source/latex/tools/ftnright.dtx

% \iffalse meta-comment
%
% Copyright 1993-2016
%
% The LaTeX3 Project and any individual authors listed elsewhere
% in this file.
%
% This file is part of the Standard LaTeX `Tools Bundle'.
% -------------------------------------------------------
%
% It may be distributed and/or modified under the
% conditions of the LaTeX Project Public License, either version 1.3c
% of this license or (at your option) any later version.
% The latest version of this license is in
%    http://www.latex-project.org/lppl.txt
% and version 1.3c or later is part of all distributions of LaTeX
% version 2005/12/01 or later.
%
% The list of all files belonging to the LaTeX `Tools Bundle' is
% given in the file `manifest.txt'.
%
% \fi
%\iffalse   % this is a METACOMMENT !
%
%% Package `ftnright' to use with LaTeX 2e
%% Copyright (C) 1989-2004 Frank Mittelbach, all rights reserved.
%<+package>\NeedsTeXFormat{LaTeX2e}[1995/06/01]
%<+package>\ProvidesPackage{ftnright}
%<+package>         [2014/10/28 v1.1f footnote layout package (FMi)]
%
% \fi
%%
%% \CheckSum{431}
%% \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         \~}
%%
%
%
%  \DoNotIndex{\;}
%^^A  \DoNotIndex{\@cclv}
%^^A  \DoNotIndex{\@colht}
%^^A  \DoNotIndex{\@colroom}
%  \DoNotIndex{\@combinedblfloats}
%  \DoNotIndex{\@combinefloats}
%  \DoNotIndex{\@dblfloatplacement}
%  \DoNotIndex{\@deferlist}
%  \DoNotIndex{\@empty}
%^^A  \DoNotIndex{\@fcolmadefalse}
%^^A  \DoNotIndex{\@firstcolumnfalse}
%^^A  \DoNotIndex{\@firstcolumntrue}
%  \DoNotIndex{\@freelist}
%  \DoNotIndex{\@ixpt}
%^^A  \DoNotIndex{\@leftcolumn}
%^^A  \DoNotIndex{\@m}
%^^A  \DoNotIndex{\@makecol}
%^^A  \DoNotIndex{\@makefntext}
%^^A  \DoNotIndex{\@maxdepth}
%  \DoNotIndex{\@midlist}
%^^A  \DoNotIndex{\@outputbox}
%^^A  \DoNotIndex{\@outputdblcol}
%^^A  \DoNotIndex{\@outputpage}
%  \DoNotIndex{\@ptsize}
%^^A  \DoNotIndex{\@setsize}
%  \DoNotIndex{\@spaces}
%^^A  \DoNotIndex{\@startcolumn}
%^^A  \DoNotIndex{\@startdblcolumn}
%  \DoNotIndex{\@tempdima}
%  \DoNotIndex{\@textbottom}
%  \DoNotIndex{\@texttop}
%^^A  \DoNotIndex{\@thefnmark}
%  \DoNotIndex{\@viiipt}
%  \DoNotIndex{\@whilesw}
%  \DoNotIndex{\@width}
%^^A  \DoNotIndex{\@xstartcol}
%  \DoNotIndex{\@xpt}
%  \DoNotIndex{\advance}
%  \DoNotIndex{\begingroup}
%  \DoNotIndex{\box}
%^^A  \DoNotIndex{\boxmaxdepth}
%^^A  \DoNotIndex{\columnseprule}
%^^A  \DoNotIndex{\columnwidth}
%  \DoNotIndex{\count}
%  \DoNotIndex{\def}
%  \DoNotIndex{\dimen}
%  \DoNotIndex{\dp}
%  \DoNotIndex{\else}
%  \DoNotIndex{\endgroup}
%  \DoNotIndex{\fi}
%  \DoNotIndex{\filedate}
%  \DoNotIndex{\filename}
%  \DoNotIndex{\fileversion}
%^^A  \DoNotIndex{\footins}
%^^A  \DoNotIndex{\footnoterule}
%^^A  \DoNotIndex{\footnotesep}
%^^A  \DoNotIndex{\footnotesize}
%^^A  \DoNotIndex{\ftn@amount}
%  \DoNotIndex{\gdef}
%  \DoNotIndex{\global}
%  \DoNotIndex{\hbox}
%  \DoNotIndex{\hfil}
%  \DoNotIndex{\hss}
%  \DoNotIndex{\ht}
%^^A  \DoNotIndex{\if@fcolmade}
%^^A  \DoNotIndex{\if@firstcolumn}
%  \DoNotIndex{\ifcase}
%^^A  \DoNotIndex{\ifvoid}
%  \DoNotIndex{\ifx}
%^^A  \DoNotIndex{\insert}
%  \DoNotIndex{\ixpt}
%  \DoNotIndex{\let}
%  \DoNotIndex{\llap}
%  \DoNotIndex{\long}
%^^A  \DoNotIndex{\maxdepth}
%^^A  \DoNotIndex{\newdimen}
%^^A  \DoNotIndex{\newskip}
%  \DoNotIndex{\noindent}
%  \DoNotIndex{\normalsize}
%  \DoNotIndex{\or}
%^^A  \DoNotIndex{\parindent}
%^^A  \DoNotIndex{\preparefootins}
%^^A  \DoNotIndex{\rcol@footinsskip}
%^^A  \DoNotIndex{\saved@footinsskip}
%  \DoNotIndex{\setbox}
%  \DoNotIndex{\skip}
%  \DoNotIndex{\space}
%^^A  \DoNotIndex{\strutbox}
%^^A  \DoNotIndex{\textheight}
%^^A  \DoNotIndex{\textwidth}
%  \DoNotIndex{\unvbox}
%  \DoNotIndex{\vbox}
%  \DoNotIndex{\viiipt}
%  \DoNotIndex{\vrule}
%  \DoNotIndex{\vskip}
%^^A  \DoNotIndex{\wlog}
%  \DoNotIndex{\xdef}
%  \DoNotIndex{\xpt}
%  \DoNotIndex{\z@}
%
% \changes{v1.1a}{1994/01/24}{Upgrades for LaTeX2e}
% \changes{v1.1b}{1994/01/24}{Driver moved in front}
% \changes{v1.1c}{1996/01/01}{Use article.cls for documentation}
%
% \renewcommand{\.}{\penalty500} %^^A for certain breaks
%
% \setlength{\hfuzz}{2pt} ^^A allow small overshot in verbatim
%
% \GetFileInfo{ftnright.sty}
%
% \title{Footnotes in a multi-column layout\thanks
%   {The \LaTeX{} package {\tt \filename} which is described
%    in this article has the version number \fileversion{} dated
%    \filedate.}}
% \author{Frank Mittelbach}
%
%
% \maketitle
%
% \pageshrink 1pt  %^^A compensate for the \thanks marker
%
%
% \section{Preface to version 1.1}
%
% The new release is a basically unchanged version of the original. I
% upgraded the macros so that they work with \LaTeXe{} and used some
% of the additional flexibility introduced therein. For example, the
% command |\preparefootins| is now automatically called at
% |\begin{document}|, thus allowing the user to adjust the
% |\textheight| in the preamble.
%
% It is not surprisingly that I was forced to change some of the
% macros because they dig deep into \LaTeX{}'s output routines.
% Fortunately this is something normally not necessary when upgrading
% other \LaTeX~2.09 styles to \LaTeXe{} packages.
%
% I also upgraded the documentation to conform to the \LaTeXe{}
% terminology, e.g., this is a package since document classes will not
% know about it. However it is very likely that i have missed some
% necessary corrections.
%
% \section{Introduction}
%
%
% The placement of footnotes in a multicolumn layout always bothered
% me. The approach taken by \LaTeX{} (i.e., placing the footnotes
% separately under each column) might be all right if nearly no
% footnotes are present. But it looks clumsy when both columns contain
% footnotes, especially when they occupy different amounts of space.
%
% In the multicolumn package~\cite{art:FMi89b}, I used page-wide
% footnotes at the bottom of the page, but again the result doesn't
% look very pleasant since short footnotes produce undesired gaps of
% white space. Of course, the main goal of this package was a
% balancing algorithm for columns which would allow switching between
% different numbers of columns on the same page. With this feature,
% the natural place for footnotes seems to be the bottom of the
% page\footnote{You cannot use column footnotes at the bottom, since
% the number of columns can differ on one page.} but looking at some
% of the results it seems best to avoid footnotes in such a layout
% entirely.
%
%
% Another possibility is to turn footnotes into endnotes, i.e.,
% printing them at the end of every chapter or the end of the entire
% document.  But I assume everyone who has ever read a book using such
% a layout will agree with me, that it is a pain to search back and
% forth, so that the reader is tempted to ignore the endnotes
% entirely.
%
% When I wrote the article about ``Future extensions of
% \TeX{}''~\cite{inproc:FMi90} I was again dissatisfied with the
% outcome of the footnotes, and since this article should show certain
% aspects of high quality typesetting, I decided to give the footnote
% problem a try and modified the \LaTeX{} output routine for this
% purpose.  The layout I used was inspired by the yearbook of the
% Gutenberg Gesellschaft Mainz \cite{book:GG}.  Later on, I found that
% it is also recommended by Jan White \cite{book:JWh88}. On the layout
% of footnotes I also consulted books by Jan Tschichold
% \cite{book:JTs87} and Manfred Simoneit \cite{book:MSi89}, books I
% would recommend to everyone being able to read German texts.
%
%
% \subsection{Description of the new layout}
%
% The result of this effort is presented in this paper and the reader
% can judge for himself whether it was successful or
% not.\footnote{Please note, that this option only changed the
% placement of footnotes. Since this article also makes use of the
% {\tt doc} package \cite{bk:GMS94}, that assigns tiny numbers to
% code lines sprinkled throughout the text, the resulting design is
% not perfect. This package is now a standard part of \LaTeXe.}
% The main idea for this layout is to assemble the
% footnotes of all columns on a page and place them all together at
% the bottom of the right column. Allowing for enough space between
% footnotes and text, and in addition, setting the footnotes in
% smaller type\footnote{The standard layout in \TUB{} uses the same
% size for footnotes and text, giving the footnotes, in my opinion,
% much too much prominence.} I decided that one could omit the
% footnote separator rule which is used in most publications prepared
% with \TeX{}.\footnote{People who prefer the rule can add it by
% redefining the command {\tt\bslash footnoterule}
% \cite[p.~156]{book:LLa86}. Please, note, that this command should
% occupy no space, so that a negative space should be used to
% compensate for the width of the rule used.} Furthermore, I decided
% to place the footnote markers\footnote{\label{thisftn}The tiny
% numbers or symbols, e.g., the `\ref{thisftn}' in front of this
% footnote.} at the baseline instead of raising them as
% superscripts.\footnote{Of course, this is done only for the mark
% preceding the footnote text and not the one used within the main
% text where a raised number or symbol set in smaller type will help
% to keep the flow of thoughts, uninterrupted.}
%
% All in all, I think this generates a neat layout, and surprisingly
% enough, the necessary changes to the \LaTeX{} output routine are
% nevertheless astonishingly simple.
%
% \subsection{The use of the package}
%
% This package might be used together with any other  package
% for \LaTeX{} which does not change the three internals changed by
% {\tt \filename}.\footnote{These are the macros {\tt\bslash
% @startcolumn}, {\tt\bslash @makecol}, and {\tt\bslash @outputdblcol},
% as we will see below.  Of course, the package will take only effect
% with a document class using a two-column layout (like {\tt ltugboat})
% or when the user additionally specifies {\tt twocolumn} as a
% document class option in the {\tt\bslash documentclass} command.} In
% most cases, it is best to use this  package as the very last
% package in the preamble to make sure that its
% settings are not overwritten by other packages.
%
% It is unfortunate that the current \LaTeX{} has nearly no provisions
% to make such changes without overwriting the internal routines. In
% the \LaTeX3 implementation, we will certainly add some hooks that
% will make such changes more easy.
%
%
% \subsection{Limitations}
%
% If in the first column there is more than a full column worth of footnote
% material the material will be split resulting in footnotes out of
% order. This issue is now detected and generates an error but the package is
% unable to gracefully handle it. This gives you two options: either rearrange
% your input so that it will use less footnotes in the first column (or add
% some pagebreaks at suitable places) or allow explicitly for more material to
% be gathered. The latter can be achieved by adding
%\begin{verbatim}
%\makeatletter
%\def\preparefootins{%
%  \global\rcol@footinsskip\skip\footins
%  \global\skip\footins\z@
%  \global\count\footins\z@
%  \global\dimen\footins2\textheight}
%\makeatother
%\end{verbatim}
% to the preamble of your document. However, with this you allow two columns
% worth of footnote material and that means that some of your footnotes are
% likely to be detached from their reference and show up on a later page!
%
% \StopEventually{
%
% \begin{small}
% \begin{thebibliography}{1}
%
% \bibitem{bk:GMS94} \textsc{M.~Goossens}, \textsc{F.~Mittelbach}
%       and \textsc{A.~Samarin}.
%       \newblock The \LaTeX{} Companion.
%       \newblock
%       Addison-Wesley, Reading, Massachusetts, 1994.
%
% \bibitem{book:GG}
% Hans-Joachim Koppitz, editor.
% \newblock {\em {Gutenberg Jahrbuch}}.
% \newblock Gutenberg-Gesellschaft, Mainz.
%
% \bibitem{book:LLa86}
% Leslie Lamport.
% \newblock {\em {\LaTeX:} A Document Preparation System}.
% \newblock Addison-Wesley, Reading, Massachusetts, 1986.
%
% \bibitem{src:ltxiii94}
% \LaTeX3 project.
% \newblock \LaTeXe distribution, 1994.
% \newblock Sources for {\LaTeXe} the successor to \LaTeX~2.09.
%
% \bibitem{art:FMi89b}
% Frank Mittelbach
% \newblock An environment for multi-column output.
% \newblock {\em TUGboat}, 10(3):407--415, November 1989.
%
% \bibitem{inproc:FMi90}
% Frank Mittelbach
% \newblock E-{\TeX}: Guidelines to future {\TeX} extensions.
% \newblock In Lincoln K. Durst, editor, {\em \TUB}, 11(3):
%   {\em 1990 TUG Annual Meeting Proceedings}, pages
%   337--345, September 1990.
%
% \bibitem{book:MSi89}
% Manfred Siemoneit.
% \newblock {\em Typographisches {G}estalten}.
% \newblock Polygraph Verlag, Frankfurt am Main, second edition, 1989.
%
% \bibitem{book:JTs87}
% Jan Tschichold.
% \newblock {\em {Ausgew\"ahlte Aufs\"atze \"uber Fragen der Gestalt des
%   Buches}}.
% \newblock Birkh\"auser Verlag, Basel, 1987.
% \newblock Second printing.
%
% \bibitem{book:JWh88}
% Jan White.
% \newblock {\em Graphic Design for the Electronic Age}.
% \newblock Watson Guptill, Xerox Press, New York, 1988.
%
% \end{thebibliography}
% \end{small}
%
%      \onecolumn
%      \PrintIndex
%      \PrintChanges
%   }
%
%
%
% \section{The documentation driver}
%
% The first bit of code contains the documentation driver file for
% \TeX{}, i.e., the file that will produce the documentation you are
% currently reading. It will be extracted from this file by the {\tt
% docstrip} program. If you don't want to make any changes to the
% presentation you can alternatively process the \texttt{.dtx} file
% directly with \LaTeXe{} to obtain the documentation.
% \changes{v1.0d}{1992/04/19}{Added driver file to source}
% \changes{v1.0e}{1993/05/13}{Added history generation}
%    \begin{macrocode}
%<*driver>
\documentclass[twocolumn]{article}

\usepackage{ftnright}
\usepackage{doc}
\AtBeginDocument{\MakeShortVerb{\|}}

\newcommand{\TUB}{{\sl TUGboat\/}}
\renewcommand\DescribeMacro[1]{\fbox
          {\PrintDescribeMacro{#1}}}
\renewcommand\DescribeEnv[1]{\fbox
          {\PrintDescribeEnv{#1}}}
\renewcommand\PrintMacroName[1]{}

\setlength{\parindent}{1em}
\setlength{\parskip}
          {2pt plus1pt minus1pt}
\setlength{\headsep}{20pt}
\setlength{\columnsep}{1.5pc}
\renewcommand{\bottomfraction}{.4}

\flushbottom
\CodelineIndex
\RecordChanges      % produce history
\EnableCrossrefs

\setcounter{IndexColumns}{2}
\IndexPrologue{\section{Index}
 All numbers denote code lines where
 the corresponding entry is used,
 underlined entries point to the
 definition.}

\begin{document}
  \DocInput{ftnright.dtx}
\end{document}
%</driver>
%    \end{macrocode}
%
% \section{The Implementation}
%
%
% As usual, we start by identifying the current version of this package
% file in the transcript file.\footnote{Nico Poppelier suggested
% omitting the {\tt\bslash typeout} statements in the production
% version of the files to avoid showing all that unnecessary
% information to the user. While I accept his criticism as valid, I
% decided that this information should at least be placed into the
% transcript file to make it easier to detect problems arising from
% the use of older versions. This happens now automatically as the command
% \texttt{\string\ProvidesPackage} will only write to the transcript file.}
% This actually happens at the very top of this file so it is commented out
% here.
%\begin{verbatim}
%\ProvidesPackage{ftnright}[\filedate\space
%               LaTeX2e package \fileversion]
%\end{verbatim}
%
% To implement the layout described, above we have to distinguish
% between the left and the right column on a page. For this purpose
% \LaTeX{} maintains the switch |\if@firstcolumn|. When assembling
% material for the left (i.e., the first) column, footnotes should
% take up no space, since they are held over for the second column. In
% the second column these footnotes are combined with the ones found
% there and placed a suitable distance from the main text at the
% bottom of this column.
%
% This means that we have to change certain parameters for the
% insertion |\footins| when we construct the second column. The right
% place to do this is in the \LaTeX{} macro |\@outputdblcol| which we
% are going to change later on.  What settings for the insertion
% parameters are appropriate? For setting the first column
% |\count|\.|\footins| and |\skip|\.|\footins| should both be zero
% since footnotes are held over while for the second column
% |\count|\.|\footins| should be $1000$ and the |\skip|\.|\footins|
% has to be set to the desired separation between main text and
% footnotes.\footnote{A value of $1000$ means that there is a
% one-to-one relationship between the real size of the footnote and
% the size finally occupied by the footnote on the current page.}
%
%
% We will allow one column of footnotes (i.e., the right column) at
% most, so that |\dimen|\.|\footins| has to equal |\textheight|. In
% principle, it would be possible to allow for even more footnotes,
% but this would complicate matters enormously.\footnote{It is not
% possible to make {\tt\bslash dimen\bslash footins} larger than
% {\tt\bslash textheight} directly, because this would result in a
% full left column (with text) and more than one column of footnotes.
% Instead, one has to make footnotes visible to the page generation
% algorithm again at the moment when a full column of footnotes is
% assembled, but we still have some space left in the first column. It
% is a nice enhancement, and, I suppose, it is of some value for
% preparing publications in certain disciplines, so here is the
% challenge~\ldots}
%
%
% \begin{macro}{\preparefootins}
% \begin{macro}{\saved@footinsskip}
%    Since a document usually starts with a left column, we have to
%    set |\count| and |\skip|\.|\footins| on top-level to zero. For
%    this purpose, we define a macro |\preparefootins| which will
%    first save the current value of |\skip|\.|\footins| in a safe
%    place. This saved value will be used later for the second column.
%    In this way, it is possible for the user or a designer of a
%    document class to adjust this parameter without fiddling with the
%    code of this package file.
%    \begin{macrocode}
%<*package>
\def\preparefootins{%
  \global\rcol@footinsskip\skip\footins
  \global\skip\footins\z@
  \global\count\footins\z@
%    \end{macrocode}
%    We will also assign |\textheight| to |\dimen|\.|\footins| to
%    allow the user to change this parameter in the preamble.
%    \begin{macrocode}
  \global\dimen\footins\textheight}
%    \end{macrocode}
%    It is necessary to make the assignments above |\global| because
%    we are going to use this macro in the output routine which has an
%    implicit grouping level to keep the changes made by it local.
%  \end{macro}
%    Of course, we have to allocate the {\sf skip} register that we
%    used above:
%    \begin{macrocode}
\newskip\rcol@footinsskip
%    \end{macrocode}
%    \end{macro}
%
%
% \begin{macro}{\@outputdblcol}
%    Now we have all the necessary tools available to tackle
%    |\@outputdblcol|.  We have to remember that when
%    |\if@firstcolumn| equals |\iftrue|, we are currently starting to
%    build the second column, i.e., that the first column is already
%    assembled. Therefore, the macro will start with the following
%    code:
%    \begin{macrocode}
\def\@outputdblcol{\if@firstcolumn
  \global\@firstcolumnfalse
%    \end{macrocode}
%    After changing the switch, we save the first column (which was
%    placed by preceding macros in |\@outputbox|) in the box register
%    |\@leftcolumn|. Since we are inside the output routine, all those
%    assignments have to be |\global| to take any effect.
%    \begin{macrocode}
  \global\setbox\@leftcolumn\box\@outputbox
%    \end{macrocode}
%    Then, we make the footnotes visible to the page generation
%    algorithm by setting |\count\footins| to $1000$ (|\@m| is an
%    abbreviation for this number) and |\skip\footins| to its saved
%    value (i.e., |\rcol@footinsskip|).
%    \begin{macrocode}
  \global\count\footins\@m
  \global\skip\footins\rcol@footinsskip
%    \end{macrocode}
%    We also have to reinsert all footnotes left over from the first
%    column to make sure that they are reconsidered by the page
%    generation algorithm of \TeX{} using the new values for |\count|
%    and |\skip|\.|\footins|. But this will be done later in the
%    macro |\@startcolumn|.
%
%    If we have just finished the right column, i.e., when
%    |\if@firstcolumn| equals |\iffalse|, we will reset the |\footins|
%    parameters as explained above using the utility macro
%    |\preparefootins|.
%    \begin{macrocode}
 \else \preparefootins
%    \end{macrocode}
%    Then, we compose both columns in |\@outputbox|, combine them with
%    all page-wide floats for this page (|\@combinedblfloats|), attach
%    header and footer, and ship out the result (|\@outputpage|).
%    Finally we look to see whether it is possible to generate
%    following pages consisting only of page-wide
%    floats.\footnote{This part is copied directly from the original
%    \LaTeX{} macro. Details about the used macros, their interfaces
%    and meanings can be found in the \LaTeXe{} source
%    code~\cite{src:ltxiii94}.}
%    \begin{macrocode}
  \global\@firstcolumntrue
  \setbox\@outputbox\vbox{\hbox to\textwidth
    {\hbox to\columnwidth
                  {\box\@leftcolumn\hss}%
     \hfil\vrule\@width\columnseprule\hfil
     \hbox to\columnwidth
                  {\box\@outputbox\hss}}}%
  \@combinedblfloats\@outputpage
  \begingroup
   \@dblfloatplacement\@startdblcolumn
   \@whilesw\if@fcolmade\fi
    {\@outputpage\@startdblcolumn}%
  \endgroup
 \fi}
%    \end{macrocode}
% \end{macro}
%
%
% \begin{macro}{\@startcolumn}
% \changes{v1.0b}{1990/08/11}{Macro added to correct float problems}
%    There is a fundamental flaw in \LaTeX's output routine for float
%    columns and float pages: split footnotes, i.e., footnotes which
%    are only partly typeset on the preceding page are not resolved.
%    They are held over until \LaTeX{} starts a page (or column)
%    containing text besides floats again. For our current layout,
%    this would mean, that if \LaTeX{} decided to make the right
%    column of a page a float column, footnotes from the left column
%    would appear on a later page. A real cure for this problem would
%    be to rewrite two-thirds of \LaTeX{}'s output routine, so I am
%    leaving this open for the interested reader.
%
% \begin{figure}[b]
%   \fbox{%^^A
% \newlength{\puzzlewd}%^^A
% \setlength{\puzzlewd}{\columnwidth}%^^A
% \addtolength{\puzzlewd}{-2.1\fboxsep}%^^A
% \begin{minipage}{\puzzlewd}
%    \vspace{17pt}
%    \begin{center}
%      \bf Puzzle:
%    \end{center}
%    \vspace{-3pt}
%    \small
%    \begin{quote}
% \rightskip \leftmargini plus 2.5em
% Given a simple \TeX{} document containing only straight text, is
% it possible for the editor,  after
% deleting one sentence, to end up with a document
% producing an extra page?
%
% We assume that the deleted text contains no \TeX{} macros and
% that the document was prepared
% with a standard macro package like the one used for \TUB\/ production.
%    \end{quote}
%    \vspace{7pt}
%    \begin{flushright}
%       The answer will be given in the next issue.
%    \end{flushright}
%    \vspace{7pt}
% \end{minipage}}
% \end{figure}
%
%    But the problem shows up even if only one float is contributed to
%    the right column since \LaTeX{} assumes that the whole column is
%    usable, whereas some of it might actually be already devoted to
%    footnotes from the left column. So we have to change the output
%    routine at least in the part that contributes floats to the next
%    column. The macro involved is called |\@startcolumn|. The first
%    thing we do is to check and see whether any deferred floats
%    exists.
%    \begin{macrocode}
\def\@startcolumn{%
 \ifx\@deferlist\@empty
%    \end{macrocode}
%    If not, we set the switch |\if@fcolmade| to {\tt false} which
%    says that we did not succeed in making a float column. Then, we
%    set |\@colroom| to |\@colht|. The register |\@colht| holds the
%    amount of space that is available for floats, text, and footnotes
%    in one column, i.e., it equals |\textheight| minus the space
%    devoted to page-wide floats. |\@colroom| is a similar register
%    which holds the value |\@colht| minus space for column floats
%    that are already contributed to the current column. Of course,
%    both values should be equal when we start a new column.
%    \begin{macrocode}
   \global\@fcolmadefalse
   \global\@colroom\@colht
 \else
%    \end{macrocode}
%    If there are floats waiting for a change to be processed, the
%    situation is more difficult. In this case, we have to reduce both
%    |\@colht| and |\@colroom| by the amount of space that will be
%    needed for the footnotes from the left column. So we must check
%    whether such footnotes are present. As we have not reinserted
%    them in |\@outputdblcol|, we can check the |\footins| box.
%    \begin{macrocode}
   \ifvoid\footins\else
%    \end{macrocode}
%    If there are some, we measure the space that will be occupied by
%    them. This measurement is not really exact. If  we have a full
%    column of footnotes, it will be too high, but this does matter
%    since we need it only for an upper bound on the free space
%    available for floats.
%    \begin{macrocode}
     \ftn@amount\ht\footins
     \advance\ftn@amount\dp\footins
     \advance\ftn@amount\skip\footins
   \fi
%    \end{macrocode}
%    We then reduce the |\@colht| by this amount and again assign
%    |\@colroom| the value of |\@colht|. If no footnotes are present,
%    we subtract zero, so there is no harm in doing this operation
%    all the time.
%    \begin{macrocode}
   \global\advance\@colht-\ftn@amount
   \global\@colroom\@colht
%    \end{macrocode}
%    Now, we call another internal \LaTeX{} macro that will try to
%    contribute floats to the next column. It will use the register
%    |\@colht| when trying to build up a float column, which is the
%    reason for reducing this register. If it succeeds, it will set the
%    switch |\if@fcolmade| to {\tt true}, otherwise, to {\tt false}. If
%    no float column is possible, it will try to place some or all of
%    the deferred floats to the top or the bottom of the next column,
%    thereby, using and reducing the value of the register |\@colroom|.
%    \begin{macrocode}
   \@xstartcol
%    \end{macrocode}
%    Afterwards, we have to restore the correct values for |\@colht|
%    and |\@colroom| again, but this time, they may differ, so that we
%    have to |\advance| both registers separately by |\ftn@amount|.
%    \begin{macrocode}
   \global\advance\@colht\ftn@amount
   \global\advance\@colroom\ftn@amount
 \fi
%    \end{macrocode}
%    Now, after doing the things depending on the status of the
%    |\@deferlist|, we have to incorporate the left over footnotes in
%    the new column. First we check whether a float column was
%    produced by |\@xstartcol| or not.
%    \begin{macrocode}
 \if@fcolmade
%    \end{macrocode}
%    If so, we do something awful. To make use of the |\@makecol|
%    macro, which attaches footnotes to |\box| $255$ and places the
%    result in the box register |\@outputbox|, we have to assign
%    |\@outputbox| (i.e., the result of |\@xstartcol|) to |\box|
%    $255$.\footnote{In German, we call this ``from the back through
%    the chest into the eyes''.}
%    \begin{macrocode}
  \setbox\@cclv\box\@outputbox
  \@makecol
 \else
%    \end{macrocode}
%    If no float column was produced, we reinsert the held over
%    footnotes so that they can be reconsidered by the page generation
%    algorithm of \TeX.  But it is necessary to ensure that this
%    operation is done only when footnotes are actually
%    present.\footnote{Otherwise, we might get an undesired extra
%    vertical space coming from {\tt\bslash skip\bslash footins}, even
%    if there are no footnotes on the page.}
%    \begin{macrocode}
   \ifvoid\footins\else
     \insert\footins{\unvbox\footins}\fi
 \fi}
%    \end{macrocode}
% \begin{macro}{\ftn@amount}
%    Of course, we also have to allocate the {\sf dimen} register. It
%    will be automatically initialized to zero.
%    \begin{macrocode}
\newdimen\ftn@amount
%    \end{macrocode}
% \end{macro}
% \end{macro}


%  \begin{macro}{\@xstartcol}
% \changes{v1.1a}{1994/01/24}{Macro reintroduced}
%    The macro |\@xtsartcol| was removed in \LaTeXe{} but we introduce
%    it here again for the moment.
%    \begin{macrocode}
\def\@xstartcol{%
  \@tryfcolumn \@deferlist
  \if@fcolmade
  \else
    \begingroup
      \let \@tempb \@deferlist
      \global \let \@deferlist \@empty
      \let \@elt \@scolelt
      \@tempb
    \endgroup
  \fi
}
%    \end{macrocode}
%  \end{macro}
%
% \begin{macro}{\@makecol}
%    The other internal macro that we have to change is |\@makecol|, a
%    macro that is called whenever one column of material is assembled
%    and column floats and footnotes have to be added. Again, we have
%    to distinguish between actions for the first and the second
%    column.
%    \begin{macrocode}
\def\@makecol{\if@firstcolumn
%    \end{macrocode}
%    For the first column, we leave the footnotes in their box and
%    simply save the contents of box $255$ in the |\box| register
%    |\@outputbox|.
%    \begin{macrocode}
  \setbox\@outputbox\box\@cclv
%    \end{macrocode}
%
%    But if the user erroneously forgot to specify a twocolumn layout, we
%    will always typeset the first column, so that the footnotes are
%    never printed.  Therefore we better check for this special case
%    and output the footnotes on a separate page in an
%    emergency.\footnote{Otherwise, the footnotes are held over for
%    ever, preventing \TeX{} from finishing the document successfully.
%    Instead, \TeX{} will produce infinity many empty pages at the end
%    of the document, trying in vain to output the held over
%    footnotes.  This problem was found by Rainer Sch\"opf when we
%    prepared the paper for the Cork conference.}
% \changes{v1.0c}{1990/08/24}{Introduced crude recovery if
%                           twocolumn false.}
% \changes{v1.0d}{1992/06/19}{Better help message}
%    \begin{macrocode}
  \if@twocolumn \else
    \ifvoid\footins \else
      \@latexerr{ftnright package
                 used in one-column mode}%
   {The ftnright package was designed to
    work with LaTeX's standard^^Jtwocolumn
    option. It does *not* work with the
    multicol package.^^JSo please specify
    `twocolumn' in the
    \noexpand\documentclass command.}%
      \shipout\box\footins \fi\fi
%    \end{macrocode}
%    What we also need to check is if there is so much footnote material that
%    it resulted in a footnote being split. If that happens the whole
%    algorithm falls apart and the footnotes get out of sync.  For the
%    moment we simply detect it here, perhaps some better scheme can be
%    implemented. One way to avoid this is to allow more than |\textheight| of
%    footnotes in |\preparefootins|. However, that isn't such a good idea
%    either as that means that a footnote from column one, might end up
%    completely on a later page.
% \changes{v1.1f}{2010/02/25}{Check for split footnotes (pr/4099)}
%    \begin{macrocode}
  \ifnum\insertpenalties>\z@
      \@latexerr{ftnright package
                 scrambled footnotes}%
    {There is too much footnote material in
     the first column  and ftnright^^Jis
     unable to cope with this.^^JYou need
     to reduce the amount to get a properly
     formatted page.}%
  \fi
 \else
%    \end{macrocode}
%    When we construct the second column, we must first check whether
%    footnotes are actually present. If not, we perform the same
%    actions as before.
%    \begin{macrocode}
  \ifvoid\footins
    \setbox\@outputbox\box\@cclv
  \else
%    \end{macrocode}
%    But, if footnotes are present, it may be possible that the whole
%    column consists of footnotes, i.e., |\box| $255$ is empty. In
%    this case, there is no use in placing any glue (|\skip\footins|)
%    in front,\footnote{In fact, it would be a mistake since this glue
%    was not taken into account when the footnotes where assembled, so
%    it would produce an overfull box.} so we have to check for this
%    possibility.
%    \begin{macrocode}
    \setbox\@outputbox\vbox
      {\ifvoid\@cclv \else
         \unvbox\@cclv
         \vskip\skip\footins\fi
%    \end{macrocode}
%    But in any case, we place the |\footnoterule| in front of the
%    footnotes even if this macro is not used by this
%    package.\footnote{This decision is certainly open to criticism,
%    since there is nothing to separate. On the other hand, a rule or
%    some other ornament in front of the footnotes is part of the
%    design which should be used consistently throughout a document.
%    As a last argument in favor of the rule, consider the situation
%    where \LaTeX{} decided to place only floats and footnotes into
%    the right hand column. In this case a separator again seems
%    adequate. In this situation one can even argue that it is
%    necessary to put in the {\tt \bslash skip\.\bslash footins}.}
%    This ends the if-statement testing whether footnotes are present
%    or not. It also ends the code which differs depending on the
%    column number.
% \changes{v1.1d}{1998/12/02}{Added the color@group macros and
%    \texttt{\protect\bslash normalcolor} to make this colorsafe}
%    \begin{macrocode}
         \color@begingroup
         \normalcolor
         \footnoterule\unvbox\footins
         \color@endgroup}\fi
  \fi
%    \end{macrocode}
%    Now the column floats are added at the top and the bottom, and
%    the |\@outputbox| is adjusted to the full column height so that
%    the glue inside will stretch in certain situations.\footnote{It
%    is an interesting question as to whether the current layout works
%    well with bottom floats or not. Actually, I would prefer to place
%    the footnotes below the bottom floats instead of above, as it is
%    done here. At least when the floats are part of the document and
%    not puzzles thrown in.  But I was too lazy to implement it
%    because I seldom use floats. If somebody implements this layout
%    (some parts of this macro have to be changed) I would be
%    interested in seeing the code and some sample results.} Again,
%    this code is copied verbatim from the original source, so I won't
%    dwell on details.\footnote{I only changed {\tt\bslash dimen128}
%    into {\tt\bslash @tempdima} which is, besides being faster and
%    shorter, only a cosmetic change. The use of this hardwired {\sf
%    dimen} register seems to indicate that this part of \LaTeX{} was
%    written very early and left unchanged since then: an interesting
%    fact for software archaeologists.}\footnote{For the \LaTeXe{}
%    upgrade I had to add the support for the
%    {\tt\string\enlargethispage} command---let's hope I did it in the
%    correct way.}
% \changes{v1.1a}{1994/01/24}{Upgrades for LaTeX2e}
%    \begin{macrocode}
  \xdef\@freelist{\@freelist\@midlist}%
  \global \let \@midlist \@empty
  \@combinefloats
  \ifvbox\@kludgeins
    \@makespecialcolbox
  \else
   \setbox\@outputbox\vbox to\@colht
     {\boxmaxdepth\maxdepth
      \@texttop
      \@tempdima\dp\@outputbox
      \unvbox\@outputbox
      \vskip-\@tempdima
      \@textbottom}%
  \fi
  \global\maxdepth\@maxdepth}
%    \end{macrocode}
% \end{macro}
%
%
% \begin{macro}{\footnotesize}
% \changes{v1.1a}{1994/01/24}{Upgrades for LaTeX2e}
%    Now we can tackle the remaining small changes to the standard
%    layout.  I decided to use a smaller size for footnotes but with a
%    slightly larger leading than usual. This means that we have to
%    redefine the |\footnotesize| macro which depends on options like
%    {\tt 11pt} etc. Fortunately, there is a simple way to find out
%    the main size of the document: the macro |\@ptsize| contains $0$,
%    $1$, or $2$ standing for $10$, $11$, or $12$ points document text
%    size.\footnote{In the new release I used the definitions from the
%    class option files \texttt{size1?.clo} and modified them
%    slightly. In the previous release there was no correction for the
%    list parameters etc., thus giving you incorrect spacing if
%    somebody used display lists in footnotes.}
%    \begin{macrocode}
\ifcase \@ptsize
\renewcommand\footnotesize{%
 \@setfontsize\footnotesize\@viiipt{9.9}%
 \abovedisplayskip 6\p@\@plus2\p@\@minus4\p@
 \abovedisplayshortskip \z@ \@plus\p@
 \belowdisplayshortskip
                    3\p@\@plus\p@\@minus2\p@
 \def\@listi{\leftmargin\leftmargini
           \topsep 3\p@ \@plus\p@ \@minus\p@
           \parsep 2\p@ \@plus\p@ \@minus\p@
           \itemsep \parsep}%
 \belowdisplayskip \abovedisplayskip
}
\or
\renewcommand\footnotesize{%
 \@setfontsize\footnotesize\@ixpt{11.1}%
 \abovedisplayskip 8\p@\@plus2\p@\@minus4\p@
 \abovedisplayshortskip \z@ \@plus\p@
 \belowdisplayshortskip
                 4\p@ \@plus2\p@ \@minus2\p@
 \def\@listi{\leftmargin\leftmargini
          \topsep 4\p@ \@plus2\p@\@minus2\p@
          \parsep 2\p@ \@plus\p@ \@minus\p@
          \itemsep \parsep}%
 \belowdisplayskip \abovedisplayskip
}
\or
\renewcommand\footnotesize{%
 \@setfontsize\footnotesize\@xpt{12.3}%
 \abovedisplayskip10\p@\@plus2\p@\@minus5\p@
 \abovedisplayshortskip \z@ \@plus3\p@
 \belowdisplayshortskip
                 6\p@ \@plus3\p@ \@minus3\p@
 \def\@listi{\leftmargin\leftmargini
         \topsep 6\p@ \@plus2\p@ \@minus2\p@
         \parsep 3\p@ \@plus2\p@ \@minus\p@
         \itemsep \parsep}%
 \belowdisplayskip \abovedisplayskip
}
\fi
%    \end{macrocode}
% \end{macro}
%
%
%
% \begin{macro}{\footnoterule}
%    Setting footnotes in smaller type and separating them with
%    sufficient space from the main text allow us to omit the
%    |\footnoterule| normally used.
%    \begin{macrocode}
\let\footnoterule\@empty
%    \end{macrocode}
% \end{macro}
%
%
%
% \begin{macro}{\footnotesep}
% \changes{v1.1a}{1994/01/24}{Upgrades for LaTeX2e}
%    Individual footnotes are separated from each other by a more or
%    less baseline skip of the text size. This can be specified with
%    the following code:
%    \begin{macrocode}
\AtBeginDocument
  {\global\footnotesep\ht\strutbox}
%    \end{macrocode}
%    The use of the \LaTeXe{} hook |\AtBeginDocument| is a big help
%    since it allows us to defer everything that might depend on user
%    setting inside the preamble to the |\begin{document}| environment
%    start.
% \end{macro}
%
%
%
% \begin{macro}{\@makefntext}
%    And finally, a small but nice change, to the mark at the
%    beginning of the footnote text. We will place it at the baseline
%    instead of raising it as a superscript. Additionally, it will get
%    a dot as punctuation.
% \changes{v1.0c}{1990/08/24}{Added dot as recommended by Tschichold.}
% \changes{v1.1e}{2000/04/14}{Don't use math mode for footnote symbol
%                             (pr/3172)}
%    \begin{macrocode}
\long\def\@makefntext#1{\parindent 1em
   \noindent\hbox to 2em{}%
   \llap{\@thefnmark.\,\,}#1}
%    \end{macrocode}
% \end{macro}
%
%
% \section{Initialisation}
%
% We defined the macro |\preparefootins| above,  but we also have to use
% it to prepare typesetting the first column. As a default for the
% separation of footnotes and text on the second column, we use the
%    following:
%    \begin{macrocode}
\setlength{\skip\footins}
          {10pt plus 5pt minus 3pt}
\AtBeginDocument{\preparefootins}
%</package>
%    \end{macrocode}
% Of course, this value can be changed by the user as
% described in the introduction.
%
% \Finale
%
%
%

\endinput