path: root/Master/texmf-dist/doc/latex/glossaries-extra/glossaries-extra-manual.tex

\documentclass[report,inlinetitle,widecs]{nlctdoc}

\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{alltt}
\usepackage{hologo}
\usepackage[colorlinks,
            hyperindex=false,
            pdfauthor={Nicola L.C. Talbot},
            pdftitle={glossaries-extra.sty: an extension to the glossaries
package},
            pdfkeywords={LaTeX,package,glossary,abbreviations}]{hyperref}
\usepackage[nogroupskip,nonumberlist]{glossaries-extra}

\makeglossaries

\GlsXtrEnableEntryUnitCounting{general}{0}{page}

\renewcommand*{\glsxtrifcounttrigger}[3]{#3}

\renewcommand*{\glslinkcheckfirsthyperhook}{%
  \ifnum\glsentrycurrcount\glslabel>0
   \setkeys{glslink}{hyper=false}%
  \fi
}

\newcommand*{\XeLaTeX}{\hologo{XeLaTeX}}
\newcommand*{\LuaLaTeX}{\hologo{LuaLaTeX}}
\newcommand*{\pdfLaTeX}{\hologo{pdfLaTeX}}

\IndexPrologue{\chapter*{\indexname}
 \addcontentsline{toc}{chapter}{\indexname}%
 \markboth{\indexname}{\indexname}}

\renewcommand*{\main}[1]{\hyperpage{#1}}
\newcommand*{\htextbf}[1]{\textbf{\hyperpage{#1}}}

\glssetcategoryattribute{general}{indexname}{htextbf}
\glssetcategoryattribute{general}{dualindex}{main}

\newglossaryentry{xindy}{
  name={\appfmt{xindy}},
  sort={xindy},
  description={An flexible indexing application with multilingual
  support written in Perl.}
}

\newglossaryentry{makeindex}{%
  name={\appfmt{makeindex}},%
  sort={makeindex},%
  description={An indexing application.},
}

\newglossaryentry{makeglossaries}{%
name={\appfmt{makeglossaries}},%
sort={makeglossaries},%
description={A custom designed Perl script interface
provided with the \styfmt{glossaries} package
to run \gls{xindy} or \gls{makeindex} according to 
the document settings.}}

\newglossaryentry{numberlist}{%
name={number list},%
description={A list of \glspl{entrylocation} (also 
called a location list). The number list can be suppressed using the 
\pkgopt{nonumberlist} package option.}
}

\newglossaryentry{entrylocation}{%
name={entry location},%
description={The location of the entry in the document. This
defaults to the page number on which the entry appears. An entry may
have multiple locations.}
}

\newglossaryentry{locationlist}{%
name={location list},%
description={A list of \glspl{entrylocation}.
See \gls{numberlist}.}%
}

\newglossaryentry{linktext}{%
name={link-text},
description={The text produced by commands such as \ics{gls}. It may
or may not have a hyperlink to the glossary.}
}

\let\glsd\glsuseri
\let\glsation\glsuserii

\newglossaryentry{firstuseflag}{%
name={first use flag},
description={A conditional that determines whether or not the entry
has been used according to the rules of \gls{firstuse}.}%
}

\newglossaryentry{firstusetext}{%
name={first use text},
description={The text that is displayed on \gls{firstuse}, which is
governed by the \gloskey{first} and \gloskey{firstplural} keys of
\ics{newglossaryentry}. (May be overridden by
\ics{glsdisp}.)}%
}

\newglossaryentry{firstuse}{%
  name={first use},
  user1={first used},
  see={firstuseflag,firstusetext},
  description={The first time a glossary entry is used (from the start
  of the document or after a reset) with one of the
  following commands: \ics{gls}, \ics{Gls}, \ics{GLS}, \ics{glspl},
  \ics{Glspl}, \ics{GLSpl} or \ics{glsdisp}.}%
}

\setcounter{IndexColumns}{2}

\newcommand*{\igloskey}[2][newglossaryentry]{\icsopt{#1}{#2}}
\newcommand*{\gloskey}[2][newglossaryentry]{\csopt{#1}{#2}}

\newcommand*{\glostyle}[1]{\textsf{#1}\index{glossary styles:>#1={\protect\sffamily#1}|main}}

\newcommand*{\acrstyle}[1]{\textsf{#1}\index{acronym
styles (glossaries):>#1={\protect\ttfamily#1}|main}}

\newcommand*{\abbrstyle}[1]{\textsf{#1}\index{abbreviation styles:>#1={\protect\sffamily#1}|main}}

\newcommand*{\category}[1]{\textsf{#1}\index{categories:>#1={\protect\sffamily#1}|main}}

\newcommand*{\catattr}[1]{\textsf{#1}\index{category attributes:>#1={\protect\sffamily#1}|main}}

\newcommand*{\postlinkcat}{%
 \cs{glsxtrpostlink}\meta{category}%
 \index{glsxtrpostlinkcategory=\cs{glsxtrpostlink}\meta{category}|hyperpage}%
}

\setlength\marginparwidth{70pt}

\begin{document}
\MakeShortVerb{"}
\DeleteShortVerb{\|}

 \title{glossaries-extra.sty v1.01:
 an extension to the glossaries package}
 \author{Nicola L.C. Talbot\\[10pt]
Dickimaw Books\\
\url{http://www.dickimaw-books.com/}}

 \date{2016-02-02}
 \maketitle

\begin{abstract}
The \styfmt{glossaries-extra} package is an extension to the
\sty{glossaries} package, providing additional features.
Some of the features provided by this package are only available
with \sty{glossaries} version 4.19 (or above).
This document assumes familiarity with the \sty{glossaries} package.

\end{abstract}

\begin{important}
Since \styfmt{glossaries-extra} internally loads the \sty{glossaries}
package, you also need to have \sty{glossaries} installed and
all the packages that \sty{glossaries} depends on (including, but
not limited to, \sty{tracklang}, \sty{mfirstuc}, \sty{etoolbox}, 
\sty{xkeyval} (at least version dated 2006/11/18), \sty{textcase},
\sty{xfor}, \sty{datatool-base} and \sty{amsgen}. These
packages are all available in the current \TeX\ Live and Mik\TeX\
distributions. If any of them are missing, please update your
\TeX\ distribution using your update manager.
(For help on this see, for example,
\href{http://tex.stackexchange.com/questions/55437/how-do-i-update-my-tex-distribution}{How do I update my \TeX\ distribution?}
or
\href{http://tex.stackexchange.com/questions/14925/updating-tex-on-linux}{Updating
\TeX\ on Linux}.)
\end{important}


\tableofcontents

\chapter{Introduction}
\label{sec:intro}

The \sty{glossaries} package is a flexible package, but it's also a
heavy-weight package that uses a lot of resources. As package
developer, I'm caught between those users who complain about the
drawbacks of a heavy-weight package with a large user manual and
those users who want more features (which necessarily adds to the
package weight and manual size).

The \styfmt{glossaries-extra} package is an attempt to provide
a~compromise for this
conflict. Version 4.21 of the \styfmt{glossaries} package is
the last version to incorporate new features. Future versions of
\styfmt{glossaries} will just be bug fixes. New features will
instead be added to \styfmt{glossaries-extra}.
This means that the base \styfmt{glossaries} package won't increase
in terms of package loading time and allocation of resources, but
those users who do want extra features available will have more of a
chance of getting their feature requests accepted.

\section{Package Defaults}
\label{sec:defaults}

I'm not happy with some of the default settings assumed by the
\sty{glossaries} package, and, judging from code I've seen, other
users also seem unhappy with them, as certain package options are
often used in questions posted on various sites. I can't change the default
behaviour of \styfmt{glossaries} as it would break backward
compatibility, but since \styfmt{glossaries-extra} is a separate
package, I have decided to implement some of these commonly-used 
options by default. You can switch them back if they're not 
appropriate.

The new defaults are:
\begin{itemize}
\item \pkgopt[true]{toc} (add the glossaries to the table of
contents). Use \pkgopt[false]{toc} to switch this back off.

\item \pkgopt[true]{nopostdot} (suppress the terminating full stop
after the description in the glossary). Use
\pkgopt[false]{nopostdot} to restore the terminating full stop
(period).

\item \pkgopt[true]{noredefwarn} (suppress warnings when
the \env{theglossary} environment and \cs{printglossary} are redefined while
\sty{glossaries} is loading). To restore the warnings, use
\pkgopt[false]{noredefwarn}. Note that this won't have any effect if
the \sty{glossaries} package has already been loaded before you use
the \styfmt{glossaries-extra} package.

\item If \sty{babel} has been loaded, the \pkgopt[babel]{translate}
option is switched on. To revert to using the \sty{translator}
interface, use \pkgopt[true]{translate}. There is no change to the
default if \sty{babel} hasn't been loaded.

\end{itemize}

Examples:
\begin{enumerate}
\item 
\begin{verbatim}
\documentclass{article}
\usepackage{glossaries-extra}
\end{verbatim}
This is like:
\begin{verbatim}
\documentclass{article}
\usepackage[toc,nopostdot]{glossaries}
\usepackage{glossaries-extra}
\end{verbatim}

\item
\begin{verbatim}
\documentclass[british]{article}
\usepackage{babel}
\usepackage{glossaries-extra}
\end{verbatim}
This is like:
\begin{verbatim}
\documentclass[british]{article}
\usepackage{babel}
\usepackage[toc,nopostdot,translate=babel]{glossaries}
\usepackage{glossaries-extra}
\end{verbatim}

\item
\begin{verbatim}
\documentclass{memoir}
\usepackage{glossaries-extra}
\end{verbatim}
This is like:
\begin{verbatim}
\documentclass{memoir}
\usepackage[toc,nopostdot,noredefwarn]{glossaries}
\usepackage{glossaries-extra}
\end{verbatim}
\emph{However}
\begin{verbatim}
\documentclass{memoir}
\usepackage{glossaries}
\usepackage{glossaries-extra}
\end{verbatim}
This is like:
\begin{verbatim}
\documentclass{memoir}
\usepackage[toc,nopostdot]{glossaries}
\usepackage{glossaries-extra}
\end{verbatim}
Since by the time \styfmt{glossaries-extra} has been loaded,
\sty{glossaries} has already redefined \cls{memoir}'s
glossary-related commands.
\end{enumerate}

Another noticeable change is that by default \cs{printglossary}
will now display information text in the document if the external
glossary file doesn't exist. This is explanatory text to help new
users who can't work out what to do next to complete the document
build. Once the document is set up correctly and the external files
have been generated, this text will disappear.

This change is mostly likely to be noticed by users
with one or more redundant empty glossaries who ignore
transcript messages, explicitly use \gls{makeindex}\slash\gls{xindy}
on just the non-empty glossary (or glossaries) and use
the iterative 
\ics{printglossaries} command instead of \ics{printglossary}. For example,
consider the following:
\begin{verbatim}
\documentclass{article}

\usepackage[acronym]{glossaries}

\makeglossaries

\newacronym{laser}{laser}{light amplification by stimulated
emission of radiation}

\begin{document}

\gls{laser}

\printglossaries

\end{document}
\end{verbatim}
The above document will only display the list of
acronyms at the place where \ics{printglossaries} occurs. However it
will also attempt to input the \texttt{.gls} file associated with
the \texttt{main} glossary.

If you use \gls{makeglossaries}, you'll get the warning message:
\begin{verbatim}
Warning: File 'test.glo' is empty.
Have you used any entries defined in glossary 'main'?
Remember to use package option 'nomain' if you
don't want to use the main glossary.
\end{verbatim}
(where the original file is called \texttt{test.tex})
but if you simply call \gls{makeindex} directly to generate the
\texttt{.acr} file (without attempting to create the \texttt{.gls}
file) then the transcript file will always contain the message:
\begin{verbatim}
No file test.gls.
\end{verbatim}
This doesn't occur with \gls{makeglossaries} as it will create
the \texttt{.gls} file containing the single command \cs{null}.

If you simply change from \sty{glossaries} to
\styfmt{glossaries-extra} in this document, you'll find a change in the
resulting PDF if you don't use \gls{makeglossaries} and you only
generate the \texttt{.acr} file with \gls{makeindex}.

The transcript file will still contain the message
about the missing \texttt{.gls}, but now you'll also see
information in the actual PDF document. The simplest remedy is to
follow the advice inserted into the document at that point, which is
to add the \pkgopt{nomain} package option:
\begin{verbatim}
\documentclass{article}

\usepackage[nomain,acronym]{glossaries-extra}

\makeglossaries

\newacronym{laser}{laser}{light amplification by stimulated
emission of radiation}

\begin{document}

\gls{laser}

\printglossaries

\end{document}
\end{verbatim}


\section{New or Modified Package Options}
\label{sec:pkgopts}

If you haven't already loaded \sty{glossaries}, you can use any of
the package options provided by \sty{glossaries} when you load
\styfmt{glossaries-extra} and they will automatically be passed to
\sty{glossaries} (which \styfmt{glossaries-extra} will load). If
\sty{glossaries} has already been loaded, then those options will be
passed to \ics{setupglossaries}, but remember that not all of the
\sty{glossaries} package options may be used in that command.

In addition to those options recognised by \sty{glossaries}, 
there are some new ones provided by \styfmt{glossaries-extra}:

\begin{description}
\item[{\pkgopt{accsupp}}] Load the \sty{glossaries-accsupp}
package (if not already loaded).

If you want to define styles that can interface with the
accessibility support provided by \sty{glossaries-accsupp} use
the \cs{glsaccess\meta{xxx}} type of commands instead of
\cs{glsentry\meta{xxx}} (for example, \ics{glsaccesstext} instead of
\ics{glsentrytext}). If \sty{glossaries-accsupp} hasn't been loaded
those commands are equivalent (for example, \cs{glsaccesstext}
just does \cs{glsentrytext}) but if it has been loaded, then the
\cs{glsaccess\meta{xxx}} commands will add the accessibility
information. (See \sectionref{sec:accsupp} for further details.)

Note that the \pkgopt{accsupp} option can only be used as 
a~package option (not through \ics{glossariesextrasetup}) since the \sty{glossaries-accsupp}
package must be loaded before \styfmt{glossaries-extra} if it's
required.

\item[{\pkgopt{undefaction}}] This is a \meta{key}=\meta{value}
option, which has two allowed values: \pkgoptfmt{warn} and
\pkgoptfmt{error}. This indicates what to do if an undefined
glossary entry is referenced. The default behaviour is
\pkgopt[error]{undefaction}, which produces an error message (the
default for \sty{glossaries}). You can switch this to a warning
message (and ?? appearing in the text) with
\pkgopt[warn]{undefaction}.

\item[{\pkgopt{docdef}}] This is a boolean option, which indicates
whether or not it's permitted for the command \ics{newglossaryentry}
to be used in the
\env{document} environment. The \sty{glossaries} package allows
\cs{newglossaryentry} within the \env{document} environment (when
used with \gls{makeindex} or \gls{xindy}) but the user manual warns 
against this usage. By default the \styfmt{glossaries-extra} package
\emph{prohibits} this, only allowing definitions within the
preamble. If you are really determined to define entries in the
\env{document} environment, despite all the associated drawbacks,
you can restore this with \pkgopt[true]{docdef}. Note that this
doesn't change the prohibitions that the \sty{glossaries}
package has in certain circumstances (for example, when using
\qt{option~1}). See the \sty{glossaries} user manual for further details.

This option affects commands that internally use
\cs{newglossaryentry}, such as \cs{newabbreviation}, but not
the \qt{on-the-fly} commands described in \sectionref{sec:onthefly}.

\item[{\pkgopt{nomissingglstext}}] This is a boolean option.
If true, this will suppress the warning text that will appear in the
document if the external glossary files haven't been generated due
to an incomplete document build. However, it's probably simpler 
just to fix whatever has caused the failure to build the external
file or files.

\item[{\pkgopt{indexcrossrefs}}] This is a boolean option.
If \pkgoptfmt{true}, this will automatically index any
cross-referenced entries that haven't been marked as used at
the end of the document. Note that this necessarily adds to
the overall document build time, especially if you have defined
a large number of entries, so this defaults to \pkgoptfmt{false},
but it will be automatically switched on if you use the \gloskey{see} key in any
entries. To force it off, even if you use the \gloskey{see}, you
need to explicitly set \pkgopt{indexcrossrefs} to \pkgoptfmt{false}.

\item[{\pkgopt{abbreviations}}] This option has no value and can't
be cancelled. If used,
it will automatically create a new glossary with the label
\texttt{abbreviations} and redefines \cs{glsxtrabbrvtype} to this
label. In addition, it defines a shortcut command
\begin{definition}[\DescribeMacro\printabbreviations]
\cs{printabbreviations}\oarg{options}
\end{definition}
which is equivalent to
\begin{alltt}
\cs{printglossary}[type=\cs{glsxtrabbrvtype},\meta{options}]
\end{alltt}
The title of the new glossary is given by
\begin{definition}[\DescribeMacro\abbreviationsname]
\cs{abbreviationsname}
\end{definition}
If this command is already defined, it's left unchanged. Otherwise
it's defined to \qt{Abbreviations} if \sty{babel} hasn't been loaded
or \cs{acronymname} if \sty{babel} has been loaded. However, if
you're using \sty{babel} it's likely you will need to change this.
(See \sectionref{sec:lang} for further details.)

\begin{important}
If you don't use the \pkgopt{abbreviations} package option,
the \cs{abbreviationsname} command won't be defined (unless it's
defined by an included language file).
\end{important}

If the \pkgopt{abbreviations} option is used and the 
\pkgopt{acronym} option provided by the \sty{glossaries}
package hasn't been used, then \ics{acronymtype}
will be set to \ics{glsxtrabbrvtype} so that acronyms defined with
\ics{newacronym} can be added to the list of abbreviations. If you
want acronyms in the \texttt{main} glossary and other abbreviations in the
\texttt{abbreviations} glossary then you will need to redefine
\cs{acronymtype} to \texttt{main}:
\begin{verbatim}
\renewcommand*{\acronymtype}{main}
\end{verbatim}

Note that there are no analogous options to the \sty{glossaries}
package's \pkgopt{acronymlists} option (or associated commands)
as the abbreviation mechanism is handled differently with
\styfmt{glossaries-extra}.

\item[{\pkgopt{symbols}}] This is passed to \sty{glossaries} but
will additionally define
\begin{definition}[\DescribeMacro\glsxtrnewsymbol]
\cs{glsxtrnewsymbol}\oarg{options}\marg{label}\marg{symbol}
\end{definition}
which is equivalent to
\begin{alltt}
\cs{newglossaryentry}\marg{label}\{name=\marg{symbol},
 sort=\marg{label},type=symbols,category=symbol,\meta{options}\}
\end{alltt}
Note that the \gloskey{sort} key is set to the \meta{label}
not the \meta{symbol} as the symbol will likely contain commands.

\item[{\pkgopt{numbers}}] This is passed to \sty{glossaries} but
will additionally define
\begin{definition}[\DescribeMacro\glsxtrnewnumber]
\cs{glsxtrnewnumber}\oarg{options}\marg{number}
\end{definition}
which is equivalent to
\begin{alltt}
\cs{newglossaryentry}\marg{label}\{name=\marg{number},
 sort=\marg{label},type=numbers,category=number,\meta{options}\}
\end{alltt}

\item[{\pkgopt{shortcuts}}] Unlike the \sty{glossaries} package
option of the same name, this option isn't boolean but has multiple
values:
\begin{itemize}
\item \pkgopt[acronyms]{shortcuts} (or \pkgopt[acro]{shortcuts}):
set the shortcuts provided by the \sty{glossaries} package for acronyms (such as \cs{ac}).

\item \pkgopt[abbreviations]{shortcuts} (or
\pkgopt[abbr]{shortcuts}):
set the abbreviation shortcuts provided by \styfmt{glossaries-extra}. (See
\sectionref{sec:abbrshortcuts}.) These settings don't switch on the
acronym shortcuts provided by the \sty{glossaries} package.

\item \pkgopt[other]{shortcuts}: set the \qt{other}
shortcut commands, but not the shortcut commands for abbreviations
or the acronym shortcuts provided by \sty{glossaries}.
The \qt{other} shortcuts are:
\begin{itemize}
\item \ics{newentry} equivalent to \ics{newglossaryentry}
\item \ics{newsym} equivalent to \ics{glsxtrnewsymbol} (see the
\pkgopt{symbols} option).
\item \ics{newnum} equivalent to \ics{glsxtrnewnumber} (see the
\pkgopt{numbers} option).
\end{itemize}

\item \pkgopt[all]{shortcuts} (or \pkgopt[true]{shortcuts}): 
define all the shortcut commands.

\item \pkgopt[none]{shortcuts} (or \pkgopt[false]{shortcuts}):
don't define any of the shortcut commands (default).
\end{itemize}

Note that multiple invocations of the \pkgopt{shortcuts} option
\emph{within the same option list} will override each other.
\end{description}

After the \styfmt{glossaries-extra} package has been loaded, you can
set available options using
\begin{definition}[\DescribeMacro\glossariesextrasetup]
\cs{glossariesextrasetup}\marg{options}
\end{definition}
The \pkgopt{abbreviations} option may only be used in the preamble.

\section{Modifications to Existing Commands or Styles}
\label{sec:modifications}

The commands used by \sty{glossaries} to automatically produce an
error if an entry is undefined (such as \ics{glsdoifexists}) are
changed to take the \pkgopt{undefaction} option into account.

The \cs{newglossaryentry} command has a new key called
\gloskey{category}, which sets the category label for the given
entry. By default this is \texttt{general}. See
\sectionref{sec:categories} for further information about
categories.

The \ics{newterm} command (defined through the \pkgopt{index} package
option) is modified so that the category defaults to \category{index}.
The \ics{newacronym} command is modified to use the new abbreviation
interface provided by \styfmt{glossaries-extra}.
(See \sectionref{sec:abbreviations}.)

\subsection{Entry Indexing}
\label{sec:wrglossary}

The \styfmt{glossaries-extra} package provides an extra key for
commands like \cs{gls} and \cs{glstext} called
\gloskey[glslink]{noindex}. This is a boolean key. If true,
this suppresses the indexing. (That is, it prevents \cs{gls} or
whatever from adding a line to the external glossary file.)
This is more useful than the \pkgopt{indexonlyfirst} package option
provided by \sty{glossaries}, as the \gls{firstuse} might not be the most
pertinent use. (If you want to apply \pkgopt{indexonlyfirst}
to selected entries, rather than all of them, you can use
the \catattr{indexonlyfirst} attribute, see
\sectionref{sec:categories} for further details.)
Note that the \gloskey[glslink]{noindex} key isn't available
for \ics{glsadd} (and \ics{glsaddall}) since the whole purpose
of that command is to index an entry.

There is a new hook that's used each time indexing information is
written to the external glossary files:
\begin{definition}[\DescribeMacro\glsxtrdowrglossaryhook]
\cs{glsxtrdowrglossaryhook}\marg{label}
\end{definition}
where \meta{label} is the entry's label. This does nothing by
default but may be redefined. (See, for example, the 
accompanying sample file \texttt{sample-indexhook.tex}, 
which uses this hook to determine which entries haven't been
indexed.)

The value of the \gloskey{see} key is now saved
as a field. This isn't the case with \sty{glossaries}, where
the \gloskey{see} attribute is simply used to directly
write a line to the corresponding glossary file and is then 
discarded. This is why the \gloskey{see} key can't be
used before \ics{makeglossaries} (since the file hasn't been opened
yet). It's also the reason why the \gloskey{see} key doesn't
have any effect when used in entries that are defined in the
\env{document} environment. Since the value isn't saved, it's not
available when the \texttt{.glsdefs} file is created at the end
of the document and so isn't available at the start of the
\env{document} environment on the next run.

This modification allows \styfmt{glossaries-extra} to provide
\begin{definition}[\DescribeMacro\glsxtraddallcrossrefs]
\cs{glsxtraddallcrossrefs}
\end{definition}
which is used at the end of the document to automatically add
any unused cross-references unless the package option
\pkgopt{indexcrossrefs} was set to false.

As a by-product of this enhancement, the \gloskey{see} key will now
work for entries defined in the document environment, but it's still
best to define entries in the preamble, and the \gloskey{see} key
still can't work before the file has been opened by
\cs{makeglossaries}.

\subsection{Entry Display Style Modifications}
\label{sec:entryfmtmods}

Recall from the \sty{glossaries} package that commands such as \cs{gls}
display text at that point in the document (optionally with a
hyperlink to the relevant line in the glossary). This text is
referred to as the \qt{\gls{linktext}} regardless of whether or not it
actually has a hyperlink. The actual text and the way it's displayed
depends on the command used (such as \cs{gls}) and the entry format.

The default entry format (\ics{glsentryfmt}) used in the
\gls{linktext} by commands like \cs{gls} (but not commands like
\cs{glstext}) is changed by \styfmt{glossaries-extra} to test for
regular entries, which are determined as follows:

\begin{itemize}
\item If an entry is assigned to a category that has the
\catattr{regular} attribute set (see \sectionref{sec:categories}), the entry is considered a~regular
entry, even if it has a~value for the \gloskey{short} key.
In this case \cs{glsentryfmt} uses \ics{glsgenentryfmt}
(provided by \sty{glossaries}), which uses the \gloskey{first}
(or \gloskey{firstplural}) value on \gls{firstuse} and the
\gloskey{text} (or \gloskey{plural}) value on subsequent use.

\item An entry that doesn't have a~value for the \gloskey{short} 
key is assumed to be a~regular entry, even if the
\catattr{regular} attribute isn't set to \qt{true} (since it can't
be an abbreviation without the short form).
In this case \cs{glsentryfmt} uses \ics{glsgenentryfmt}.

\item If an entry does has a~value for the \gloskey{short} key
and hasn't been marked as a~regular entry through the 
\catattr{regular} attribute, it's not
considered a regular entry. 
In this case \cs{glsentryfmt} uses \ics{glsxtrgenabbrvfmt}
(defined by \styfmt{glossaries-extra}) which is governed
by the abbreviation style (see \sectionref{sec:abbrstyle}).

\end{itemize}

This means that entries with a short
form can be treated as regular entries rather than
abbreviations if it's more appropriate for the desired style.

The \cs{glspostlinkhook} provided by the \sty{glossaries} package to
insert information after the \gls{linktext} produced by commands like \cs{gls} and \cs{glstext} is
redefined to
\begin{definition}[\DescribeMacro\glsxtrpostlinkhook]
\cs{glsxtrpostlinkhook}
\end{definition}
This command will discard a following full stop (period) if the
\catattr{discardperiod} attribute is set to \qt{true} for the
current entry's category. It will also do
\begin{definition}[\DescribeMacro\glsxtrpostlink]
\cs{glsxtrpostlink}
\end{definition}
if a full stop hasn't be discarded and
\begin{definition}[\DescribeMacro\glsxtrpostlinkendsentence]
\cs{glsxtrpostlinkendsentence}
\end{definition}
if a full stop has been discarded.

By default \cs{glsxtrpostlink} just does \postlinkcat\ if it exists, where
\meta{category} is the category label for the current entry.
(For example,  for the \category{general} category, 
\cs{glsxtrpostlinkgeneral} if it has been defined.)

The sentence-ending hook is slightly more complicated.
If the command \postlinkcat\ is defined the hook will do that
and then insert a full stop with the space factor adjusted to match
the end of sentence. If \postlinkcat\ hasn't
been defined, the space factor is adjusted to match the end of
sentence. This means that if you have, for example, an entry that
ends with a full stop, a redundant following full stop will be
discarded and the space factor adjusted (in case the entry is in
uppercase) unless the entry is followed by additional material, in
which case the following full stop is no longer redundant and needs
to be reinserted.

There are some convenient commands you might want to use
when customizing the post-\gls{linktext} category hooks:
\begin{definition}[\DescribeMacro\glsxtrpostlinkAddDescOnFirstUse]
\cs{glsxtrpostlinkAddDescOnFirstUse}
\end{definition}
This will add the description in parentheses on \gls{firstuse}.

For example, suppose you want to append the description in
parentheses on \gls{firstuse} for entries in the \category{symbol}
category:
\begin{verbatim}
\newcommand*{\glsxtrpostlinksymbol}{%
  \glsxtrpostlinkAddDescOnFirstUse
}
\end{verbatim}

\begin{definition}[\DescribeMacro\glsxtrpostlinkAddSymbolOnFirstUse]
\cs{glsxtrpostlinkAddSymbolOnFirstUse}
\end{definition}
This will append the symbol (if defined) in parentheses on
\gls{firstuse}.

If you want to provide your own custom format be aware that you
can't use \ics{ifglsused} within the post-\gls{linktext} hook as by this point
the \gls{firstuseflag} will have been unset. Instead you can use
\begin{definition}[\DescribeMacro\glsxtrifwasfirstuse]
\cs{glsxtrifwasfirstuse}\marg{true}\marg{false}
\end{definition}
This will do \meta{true} if the last used entry was the
\gls{firstuse}
for that entry, otherwise it will do \meta{false}. (Requires at
least \sty{glossaries} v4.19 to work properly.) This command is
locally set by commands like \cs{gls}, so don't rely on it outside
of the post-\gls{linktext} hook.

\begin{important}
Note that commands like \ics{glsfirst} and \ics{glsxtrfull} fake
\gls{firstuse} for the benefit of the post-\gls{linktext} hooks by setting 
\cs{glsxtrifwasfirstuse} to \cs{@firstoftwo}.
(Although, depending on the styles in use, they may not exactly match
the text produced by \ics{gls}-like commands on \gls{firstuse}.)
\end{important}

For example, if you want to place the description in a footnote
after the \gls{linktext} on \gls{firstuse} for the \category{general} category:
\begin{verbatim}
\newcommand*{\glsxtrpostlinkgeneral}{%
  \glsxtrifwasfirstuse{\footnote{\glsentrydesc{\glslabel}}}{}%
}
\end{verbatim}

The \abbrstyle{postfootnote} abbreviation style uses the 
post-\gls{linktext} hook to
place the footnote after trailing punctuation characters.

You can set the default options used by \ics{glslink}, \ics{gls}
etc with:
\begin{definition}[\DescribeMacro\GlsXtrSetDefaultGlsOpts]
\cs{GlsXtrSetDefaultGlsOpts}\marg{options}
\end{definition}
For example, if you mostly don't want to index entries then
you can do:
\begin{verbatim}
\GlsXtrSetDefaultGlsOpts{noindex}
\end{verbatim}
and then use, for example, \verb|\gls[noindex=false]{sample}|
when you actually want the location added to the \gls{numberlist}.
These defaults may be overridden by other settings (such as
category attributes) in addition to any settings passed in the 
option argument of commands like \cs{glslink} and \cs{gls}.

Note that if you don't want \emph{any} indexing, just omit
\cs{makeglossaries} and \cs{printglossaries} (or analogous
commands).

Commands like \ics{gls} have star (\texttt{*}) and plus 
(\texttt{+}) modifiers as a short cut for \texttt{hyper=false}
and \texttt{hyper=true}. The \styfmt{glossaries-extra} package
provides a way to add a third modifier, if required, using
\begin{definition}[\DescribeMacro\GlsXtrSetAltModifier]
\cs{GlsXtrSetAltModifier}\marg{char}\marg{options}
\end{definition}
where \meta{char} is the character used as the modifier and
\meta{options} is the default set of options (which may be
overridden). Note that \meta{char} must be a single character
(not a UTF-8 character, unless you are using \XeLaTeX\ or
\LuaLaTeX).

\begin{important}
When choosing the character \meta{char} take care of any
changes in category code.
\end{important}

Example:
\begin{verbatim}
\GlsXtrSetAltModifier{!}{noindex}
\end{verbatim}
This means that \verb|\gls!{sample}| will be equivalent to
\verb|\gls[noindex]{sample}|. It's not possible to mix modifiers.
For example, if you want to do 
\begin{verbatim}
\gls[noindex,hyper=false]{sample}
\end{verbatim}
you can use \verb|\gls*[noindex]{sample}| or
\verb|\gls![hyper=false]{sample}| but you can't combine the
\texttt{*} and \texttt{!} modifiers.

\subsection{Entry Counting Modifications}
\label{sec:entrycountmods}

The \ics{glsenableentrycount} command is modified to allow
for the \catattr{entrycount} attribute. This means that
you not only need to enable entry counting with
\cs{glsenableentrycount}, but you also need
to set the appropriate attribute (see \sectionref{sec:categories}).

For example, instead of just doing:
\begin{verbatim}
\glsenableentrycount
\end{verbatim}
you now need to do:
\begin{verbatim}
\glsenableentrycount
\glssetcategoryattribute{abbreviation}{entrycount}{1}
\end{verbatim}
This will enable the entry counting for entries in the
\category{abbreviation} category, but any entries assigned to
other categories will be unchanged.

Further information about entry counting, including the
new per-unit feature, is described in \sectionref{sec:entrycount}.

\subsection{Nested Links}
\label{sec:nested}

Complications arise when you use \ics{gls} in the 
value of the \gloskey{name} field (or \gloskey{text} 
or \gloskey{first} fields, if set). This tends to occur with
abbreviations that extend other abbreviations. For example,
SHTML is an abbreviation for SSI enabled HTML, where SSI
is an abbreviation for Server Side Includes and HTML
is an abbreviation for Hypertext Markup Language.

Things can go wrong if we try the following with the
\sty{glossaries} package:
\begin{verbatim}
\newacronym{ssi}{SSI}{Server Side Includes}
\newacronym{html}{HTML}{Hypertext Markup Language}
\newacronym{shtml}{S\gls{html}}{\gls{ssi} enabled \gls{html}}
\end{verbatim}

The main problems are:
\begin{enumerate}
\item The first letter upper casing commands, such as \ics{Gls},
won't work for the \texttt{shtml} entry on \gls{firstuse} if the
long form is displayed before the short form (which is the
default abbreviation style). This will attempt to do
\begin{verbatim}
\gls{\uppercase ssi} enabled \gls{html}
\end{verbatim}
which just doesn't work. Grouping the \verb|\gls{ssi}| doesn't
work either as this will effectively try to do
\begin{verbatim}
\uppercase{\gls{ssi}} enabled \gls{html}
\end{verbatim}
This will upper case the label \texttt{ssi} so the entry won't be
recognised. This problem will also occur if you use the all capitals
version, such as \ics{GLS}.

\item The long and abbreviated forms accessed through
\ics{glsentrylong} and \ics{glsentryshort} are no longer expandable
and so can't be used be used in contexts that require this,
such as PDF bookmarks.

\item The \texttt{shtml} entry produces inconsistent results
depending on whether the \texttt{ssi} or \texttt{html} entries have
been used. Suppose both \texttt{ssi} and \texttt{html} are used
before \texttt{shtml}. For example:
\begin{verbatim}
This section discusses \gls{ssi}, \gls{html} and \gls{shtml}.
\end{verbatim}
This produces:
\begin{quote}
This section discusses server side includes (SSI), hypertext markup
language (HTML) and SSI enabled HTML (SHTML).
\end{quote}
So the \gls{firstuse} of the \texttt{shtml} entry produces
\qt{SSI enabled HTML (SHTML)}.

Now let's suppose the \texttt{html} entry is used before the
\texttt{shtml} but the \texttt{ssi} entry is used after the
\texttt{shtml} entry, for example:
\begin{verbatim}
The sample files are either \gls{html} or \gls{shtml}, but let's
first discuss \gls{ssi}.
\end{verbatim}
This produces:
\begin{quote}
The sample files are either hypertext markup language (HTML) or
server
side includes (SSI) enabled HTML (SHTML), but let’s first discuss
SSI.
\end{quote}
So the \gls{firstuse} of the \texttt{shtml} entry now produces
\qt{server side includes (SSI) enabled HTML (SHTML)}, which looks
a bit strange.

Now let's suppose the \texttt{shtml} entry is used before (or
without) the other two entries:
\begin{verbatim}
This article is an introduction to \gls{shtml}.
\end{verbatim}
This produces:
\begin{quote}
This article is an introduction to server side includes (SSI)
enabled hypertext markup language (HTML) (SHTML).
\end{quote}
So the \gls{firstuse} of the \texttt{shtml} entry now produces
\qt{server side includes (SSI) enabled hypertext markup language (HTML) 
(SHTML)}, which is even more strange.

This is all aggravated by setting the style using
\cs{setacronymstyle}. For example:
\begin{verbatim}
\setacronymstyle{long-short}
\end{verbatim}
as this references the label through the use of \cs{glslabel}
when displaying the long and short forms, but this value
changes with each use of \cs{gls}, so instead of displaying
\qt{(SHTML)} at the end of the \gls{firstuse}, it now displays
\qt{(HTML)}, since \cs{glslabel} has been changed to \texttt{html}
by \verb|\gls{html}|.

Another oddity occurs if you reset the \texttt{html} entry between
uses of the \texttt{shtml} entry. For example:
\begin{verbatim}
\gls{shtml} ... \glsreset{html}\gls{shtml}
\end{verbatim}
The next use of \texttt{shtml} produces \qt{Shypertext markup
language (HTML)}, which is downright weird.

Even without this, the short form has nested formatting commands,
which amount to \verb|\acronymfont{S\acronymfont{HTML}}|. This
may not be a problem for some styles, but if you use one of the 
\qt{sm} styles (that use \ics{textsmaller}), this will produce
an odd result.

\item Each time the \texttt{shtml} entry is used, the 
\texttt{html} entry will also be indexed and marked as used,
and on \gls{firstuse} this will happen to both the \texttt{ssi}
and \texttt{html} entries.  This kind of duplication in the location
list isn't usually particularly helpful to the reader.

\item If \sty{hyperref} is in use, you'll get nested hyperlinks
and there's no consistent way of dealing with this across the 
available PDF viewers. If on the \gls{firstuse} case, the user
clicks on the \qt{HTML} part of the \qt{SSI enabled HTML (SHTML)}
link, they may be directed to the HTML entry in the glossary or 
they may be directed to the SHTML entry in the glossary.

\end{enumerate}

For these reasons it's better to use the simple expandable commands like
\ics{glsentrytext} or \ics{glsentryshort} in the definition
of other entries (although that doesn't fix the first problem).
Alternatively use something like:
\begin{verbatim}
\newacronym
 [description={\acrshort{ssi} enabled \acrshort{html}}]
 {shtml}{SHTML}{SSI enabled HTML}
\end{verbatim}
with \sty{glossaries} or:
\begin{verbatim}
\newabbreviation
 [description={\glsxtrshort{ssi} enabled \glsxtrshort{html}}]
 {shtml}{SHTML}{SSI enabled HTML}
\end{verbatim}
with \styfmt{glossaries-extra}. This fixes all the above
listed problems (as long as you don't use \ics{glsdesc}).
Note that replacing \cs{gls} with \cs{acrshort} in the original
example may fix the \gls{firstuse} issue, but it doesn't
fix any of the other problems listed above.

However if you're really determined to use
\ics{gls} in a field that may be included within 
some \gls{linktext}, \styfmt{glossaries-extra} patches internals
used by the linking commands so that if \cs{gls} (or plural or
case changing variants) occurs in the \gls{linktext} it will
behave as though you used 
\texttt{\ics{glstext}[hyper=false,noindex]}
instead. Grouping is also added so that, for example, when
\verb|\gls{shtml}| is used for the first time the long form
\begin{verbatim}
\gls{ssi} enabled \gls{html}
\end{verbatim}
is treated as
\begin{verbatim}
{\glstext[hyper=false,noindex]{ssi}} enabled 
{\glstext[hyper=false,noindex]{html}}
\end{verbatim}
This overcomes the last three problems listed 
above, but still doesn't fix the first two.

Additionally, any instance of the long form commands, such
as \ics{glsxtrlong} or \ics{acrlong} will be temporarily
redefined to just use
\begin{alltt}
\{\ics{glsentrylong}\marg{label}\meta{insert}\}
\end{alltt}
(or case-changing versions). Similarly the short form commands,
such as \ics{glsxtrshort} or \ics{acrshort} will use
\ics{glsentryshort} in the argument of either \cs{glsabbrvfont}
(for \cs{glsxtrshort}) or \cs{acronymfont} (for \cs{acrshort}).
So if the \texttt{shtml} entry had instead been defined as:
\begin{verbatim}
\newacronym{shtml}{SHTML}{\acrshort{ssi} enabled \acrshort{html}}
\end{verbatim}
then (using the \abbrstyle{long-short} style) the \gls{firstuse} 
will be like
\begin{verbatim}
{\acronymfont{\glsentryshort{ssi}}} enabled 
{\acronymfont{\glsentryshort{html}}} (SHTML)
\end{verbatim}
whereas if the entry is defined as:
\begin{verbatim}
\newabbreviation{shtml}{SHTML}{\glsxtrshort{ssi} enabled
\glsxtrshort{html}}
\end{verbatim}
then the \gls{firstuse} will be like:
\begin{verbatim}
{\glsabbrvfont{\glsentryshort{ssi}}} enabled 
{\glsabbrvfont{\glsentryshort{html}}} (SHTML)
\end{verbatim}
Note that the first optional argument of
\cs{acrshort} or \cs{glsxtrshort} is ignored in this context. 
(The final optional argument will be inserted, if present.)
The abbreviation style that governs \ics{glsabbrvfont} will be 
set for \ics{glsxtrshort}. Note that \cs{acrshort} doesn't
set the abbreviation style.

\begin{important}
If you use any of the case-changing commands, such as \ics{Gls}
or \ics{Glstext}, (either all caps or first letter upper casing)
don't use any of the linking commands, such as \ics{gls} or
\ics{glstext}, in the definition of entries for any of the
fields that may be used by those case-changing commands.
\end{important}

\subsection{Acronym Style Modifications}
\label{sec:acronymmods}

The \styfmt{glossaries-extra} package provides a new way of dealing
with abbreviations and redefines \ics{newacronym} to
use \cs{newabbreviation} (see \sectionref{sec:abbreviations}).
If you want to restore the generic acronym function provided
by \sty{glossaries} you need to use
\begin{definition}[\DescribeMacro\RestoreAcronyms]
\cs{RestoreAcronyms}
\end{definition}
but be careful using this if you also want abbreviations as
they will clash if you attempt to use them in the same glossary as
generic acronyms from the \sty{glossaries} package.

\begin{definition}[\DescribeMacro\glsacspace]
\cs{glsacspace}\marg{label}
\end{definition}
The space command \cs{glsacspace} used by the
\acrstyle{long-sp-short} acronym style provided by \sty{glossaries}
is modified so that it uses
\begin{definition}[\DescribeMacro\glsacspacemax]
\cs{glsacspacemax}
\end{definition}
instead of the hard-coded 3em. This is a command not a length
and so can be changed using \cs{renewcommand}.

The \gls{firstuse} acronym font command
\begin{definition}[\firstacronymfont]
\cs{firstacronymfont}\marg{text}
\end{definition}
is redefined to use the \gls{firstuse} abbreviation font command
\ics{glsfirstabbrvfont}. This will be reset if you use
\cs{RestoreAcronyms}.

The subsequent use acronym font command
\begin{definition}[\acronymfont]
\cs{acronymfont}\marg{text}
\end{definition}
is redefined to use the subsequent use abbreviation font command
\ics{glsabbrvfont}. This will be reset if you use
\cs{RestoreAcronyms}.

\subsection{Glossary Style Modifications}
\label{sec:glosstylemods}

The default value of \ics{glslistdottedwidth} is changed so that
it's set at the start of the document (if it hasn't been changed in
the preamble). This should take into account situations where
\cs{hsize} isn't set until the start of the document.

The commands \ics{glossentryname} and \ics{glossentrydesc} are
modified to take into account the \catattr{glossname} and
\catattr{glossdesc} attributes (see \sectionref{sec:categories}).
This means you can make simple case-changing modifications to
the name and description without defining a new glossary style.

There is a hook after \ics{glossentryname} and 
\ics{Glossentryname}:
\begin{definition}[\DescribeMacro\glsxtrpostnamehook]
\cs{glsxtrpostnamehook}\marg{label}
\end{definition}
By default this checks the \catattr{indexname} attribute.
If the attribute exists for the category to which the label belongs,
then the name is automatically indexed using
\begin{definition}
\ics{glsxtrdoautoindexname}\marg{label}\texttt{\{indexname\}}
\end{definition}
See \sectionref{sec:autoindex} for further details.

The post-description code used within the glossary is modified so
that it also does
\begin{definition}[\DescribeMacro\glsxtrpostdescription]
\cs{glsxtrpostdescription}
\end{definition}
This occurs before the original \cs{glspostdescription}, so if the
\pkgopt[false]{nopostdot} option is used, it will be inserted before
the terminating full stop.

This new command will do \cs{glsxtrpostdesc\meta{category}}
if it exists, where \meta{category} is the category label associated
with the current entry. For example \cs{glsxtrpostdescgeneral}
for entries with the category set to \category{general}
or \cs{glsxtrpostdescacronym} for entries with the category set to
\category{acronym}.

Since both \cs{glossentry} and \cs{subglossentry} set
\begin{definition}[\DescribeMacro\glscurrententrylabel]
\cs{glscurrententrylabel}
\end{definition}
to the label for the current entry, you can use this within the
definition of these post-description hooks if you need to reference
the label.

For example, suppose you want to insert the plural form in brackets
after the description in the glossary, but only for entries in the
\category{general} category, then you could do:
\begin{verbatim}
\renewcommand{\glsxtrpostdescgeneral}{\space
 (plural: \glsentryplural{\glscurrententrylabel})}
\end{verbatim}
This means you don't have to define a custom glossary style, which
you may find more complicated. (It also allows more flexibility if
you decide to change the underlying glossary style.)

\begin{important}
This feature can't be used for glossary styles that ignore
\cs{glspostdescription} or if you redefine
\cs{glspostdescription} without including \cs{glsxtrpostdescription}.
(For example, if you redefine \cs{glspostdescription} to do
nothing instead of using the \pkgopt{nopostdot} option to suppress
the terminating full stop.)
\end{important}

\chapter{Abbreviations}
\label{sec:abbreviations}

Abbreviations include acronyms (words formed from initial letters,
such as \qt{laser}),
initialisms (initial letters of a phrase, such as \qt{html}, that
aren't pronounced as words) and contractions (where
parts of words are omitted, often replaced by an apostrophe, such as
\qt{don't}).
The \qt{acronym} code provided by the \sty{glossaries} package is
misnamed as it's more often than not used for initialisms instead.
Acronyms tend not to be \emph{expanded} on \gls{firstuse} (although they may
need to be \emph{described} for readers unfamiliar with the term). They are therefore more like a regular term,
which may or may not require a description in the glossary.

The \styfmt{glossaries-extra} package corrects this misnomer, and
provides better abbreviation handling, with
\begin{definition}[\DescribeMacro\newabbreviation]
\cs{newabbreviation}\oarg{options}\marg{label}\marg{short}\marg{long}
\end{definition}

This sets the \gloskey{category} key to \texttt{abbreviation} by
default, but that value may be overridden in \meta{options}.
The category may have attributes that modify the way abbreviations
are defined. For example, the \catattr{insertdots} attribute will
automatically insert full stops (periods) into \meta{short} or the
\catattr{noshortplural} attribute will set the default value
of the \gloskey{shortplural} key to just \meta{short} (without
appending the plural suffix). See \sectionref{sec:categories} for
further details.

See \sectionref{sec:nested} regarding the pitfalls of using
commands like \ics{gls} or \ics{glsxtrshort} within
\meta{short} or \meta{long}.

\begin{important}
Make sure that you set the category attributes before defining new
abbreviations or they may not be correctly applied.
\end{important}

The \ics{newacronym} command provided by the \sty{glossaries}
package is redefined to use
\cs{newabbreviation} with the \gloskey{category} set to
\texttt{acronym}. If you want to restore the original behaviour of
acronyms (as implemented by the \sty{glossaries} package's
\cs{newacronym}, \ics{setacronymstyle} and \ics{newacronymstyle})
you need to use
\begin{definition}[\DescribeMacro\RestoreAcronyms]
\cs{RestoreAcronyms}
\end{definition}
However, if you do this take care not to mix acronyms with other
types of entries within the same glossary. (You may also need to
redefine \ics{acronymtype}.)

The \cs{newabbreviation} command is superficially similar to the
\sty{glossaries} package's \cs{newacronym} but you can apply
different styles to different categories. The default style is
\abbrstyle{short} for entries in the \category{acronym} category and 
\abbrstyle{short-long} for entries in the \category{abbreviation}
category. (These aren't the same as the acronym styles provided by
the \sty{glossaries} package, although they may produce similar
results.)

The short form is displayed within commands like \cs{gls} using
\begin{definition}[\DescribeMacro\glsfirstabbrvfont]
\cs{glsfirstabbrvfont}\marg{short-form}
\end{definition}
on \gls{firstuse} and
\begin{definition}[\DescribeMacro\glsabbrvfont]
\cs{glsabbrvfont}\marg{short-form}
\end{definition}
for subsequent use.

\begin{important}
These commands (\cs{glsfirstabbrvfont} and \cs{glsabbrvfont}) are
reset by the abbreviation styles and whenever an abbreviation is
used by commands like \cs{gls} (but not by commands like
\ics{glsentryshort}) so don't try redefining them outside of an
abbreviation style.
\end{important}

If you use the \abbrstyle{long-short} style,
\cs{glsabbrvfont} is redefine to use
\begin{definition}[\DescribeMacro\glsabbrvdefaultfont]
\cs{glsabbrvdefaultfont}\marg{text}
\end{definition}
whereas the \abbrstyle{long-short-sc} style redefines
\cs{glsabbrvfont} to use \cs{glsxtrscfont}. If you want to use a different
font-changing command you can either redefine \cs{glsabbrvdefaultfont} and
use one of the base styles, such as \abbrstyle{long-short}, or
define a new style in a similar manner to the \qt{sc}, \qt{sm}
or \qt{em} styles.

All predefined abbreviation styles redefine \cs{glsfirstabbrvfont}
to use
\begin{definition}[\DescribeMacro\glsfirstabbrvdefaultfont]
\cs{glsfirstabbrvdefaultfont}\marg{short-form}
\end{definition}
By default, this just does \cs{glsabbrvfont}\marg{short-form}
so the \gls{firstuse} format matches the subsequence use format
for the short form.

The commands that display the full form for abbreviations use 
\cs{glsfirstabbrvfont} to display the short form and
\begin{definition}[\DescribeMacro\glsfirstlongfont]
\cs{glsfirstlongfont}\marg{long-form}
\end{definition}
to display the long form. As with \ics{glsabbrvfont}, this command
is changed by all styles. Currently all predefined abbreviation
styles provided by \styfmt{glossaries-extra} redefine
\cs{glsfirstlongfont} to use
\begin{definition}[\DescribeMacro\glsfirstlongdefaultfont]
\cs{glsfirstlongdefaultfont}\marg{long-form}
\end{definition}
You can redefine this command if you want to change the font used by
the long form on \gls{firstuse} for all your abbreviations, or you can
define your own abbreviation style that provides a different format
for only those abbreviations defined with that style.

There are two types of full forms. The display full form, which is
used on \gls{firstuse} by commands like \ics{gls} and the inline full
form, which is used by commands like \ics{glsxtrfull}.
For some of the abbreviation styles, such as \abbrstyle{long-short}, the display and inline forms
are the same. In the case of styles such as \abbrstyle{short} or
\abbrstyle{footnote}, the display and inline full forms are different.

These formatting commands aren't stored in the \gloskey{short},
\gloskey{shortplural}, \gloskey{long} or \gloskey{longplural}
fields, which means they won't be used within commands like 
\cs{glsentryshort} (but they are used within commands like
\cs{glsxtrshort} and \cs{glsfmtshort}).
Note that \ics{glsxtrlong} and the case-changing variants don't use
\cs{glsfirstlongfont}.

\section{Tagging Initials}
\label{sec:tagging}

If you would like to tag the initial letters in the long form
such that those letters are underlined in the glossary but
not in the main part of the document, you can use
\begin{definition}[\DescribeMacro\GlsXtrEnableInitialTagging]
\cs{GlsXtrEnableInitialTagging}\marg{categories}\marg{cs}
\end{definition}
before you define your abbreviations.

This command (robustly) defines \meta{cs} (a control sequence) 
to accept a single argument, which is the letter (or letters)
that needs to be tagged. The normal behaviour of this command
within the document is to simply do its argument, but in the
glossary it's activated for those categories that have
the \catattr{tagging} attribute set to \qt{true}. For those
cases it will use
\begin{definition}[\DescribeMacro\glsxtrtagfont]
\cs{glsxtrtagfont}\marg{text}
\end{definition}
This command defaults to \ics{underline}\marg{text}
but may be redefined as required.

The control sequence \meta{cs} can't already be defined when
used with the unstarred version of 
\cs{GlsXtrEnableInitialTagging} for safety reasons.
The starred version will overwrite any previous definition
of \meta{cs}. As with redefining any commands, ensure that
you don't redefine something important. In fact, just forget
the existence of the starred version and let's pretend I didn't
mention it.

The first argument of \cs{GlsXtrEnableInitialTagging} is a
comma-separated list of category names. The \catattr{tagging}
attribute will automatically be set for those categories.
You can later set this attribute for other categories (see
\sectionref{sec:categories}) but this must be done before the
glossary is displayed.

The accompanying sample file \texttt{sample-mixtures.tex}
uses initial tagging for both the \category{acronym} and
\category{abbreviation} categories:
\begin{verbatim}
\GlsXtrEnableInitialTagging{acronym,abbreviation}{\itag}
\end{verbatim}
This defines the command \cs{itag} which can be used in the
definitions. For example:
\begin{verbatim}
\newacronym
 [description={a system for detecting the location and
 speed of ships, aircraft, etc, through the use of radio
 waves}% description of this term
 ]
 {radar}% identifying label
 {radar}% short form (i.e. the word)
 {\itag{ra}dio \itag{d}etection \itag{a}nd \itag{r}anging}

\newabbreviation{xml}{XML}
 {e\itag{x}tensible \itag{m}arkup \itag{l}anguage}
\end{verbatim}
The underlining of the tagged letters only occurs in the
glossary and then only for entries with the \catattr{tagging}
attribute set.

\section{Abbreviation Styles}
\label{sec:abbrstyle}

The abbreviation style must be set before abbreviations are defined
using:
\begin{definition}[\DescribeMacro\setabbreviationstyle]
\cs{setabbreviationstyle}\oarg{category}\marg{style-name}
\end{definition}
where \meta{style-name} is the name of the style and \meta{category}
is the category label (\texttt{abbreviation} by default). New
abbreviations will pick up the current style according to their
given category. If there is no style set for the category, the
fallback is the style for the \texttt{abbreviation} category.
Some styles may automatically modify one or more of the attributes
associated with the given category. For example, the
\abbrstyle{long} and \abbrstyle{short} styles set the
\catattr{regular} attribute to \texttt{true}.

\begin{important}
If you want to apply different styles to groups of abbreviations,
assign a different category to each group and set the style for the
given category.
\end{important}

Note that \ics{setacronymstyle} is disabled by
\styfmt{glossaries-extra}. Use
\begin{alltt}
\cs{setabbreviationstyle}[acronym]\marg{style-name}
\end{alltt}
instead. The original acronym interface can be restored with
\cs{RestoreAcronyms} (see \sectionref{sec:acronymmods}).

Abbreviations can be used with the standard \sty{glossaries}
commands, such as \ics{gls}, but don't use the acronym commands
like \ics{acrshort} (which use \ics{acronymfont}). The short form can be
produced with:
\begin{definition}[\DescribeMacro\glsxtrshort]
\cs{glsxtrshort}\oarg{options}\marg{label}\oarg{insert}
\end{definition}
(Use this instead of \ics{acrshort}.)

The long form can be produced with
\begin{definition}[\DescribeMacro\glsxtrlong]
\cs{glsxtrlong}\oarg{options}\marg{label}\oarg{insert}
\end{definition}
(Use this instead of \ics{acrlong}.)

The \emph{inline} full form can be produced with
\begin{definition}[\DescribeMacro\glsxtrfull]
\cs{glsxtrfull}\oarg{options}\marg{label}\oarg{insert}
\end{definition}
(This this instead of \ics{acrfull}.)

As mentioned earlier, the inline full form may not necessarily match the format used on
\gls{firstuse} with \cs{gls}. For example, the \abbrstyle{short} style
only displays the short form on \gls{firstuse}, but the full
form will display the long form followed by the short form in
parentheses.

\begin{important}
If you want to use an abbreviation in a chapter or section
title, use the commands described in \sectionref{sec:headtitle}
instead.
\end{important}

The arguments \meta{options}, \meta{label} and \meta{insert} are the
same as for commands such as \cs{glstext}. There are also analogous
case-changing commands:

First letter upper case short form:
\begin{definition}[\DescribeMacro\Glsxtrshort]
\cs{Glsxtrshort}\oarg{options}\marg{label}\oarg{insert}
\end{definition}

First letter upper case long form:
\begin{definition}[\DescribeMacro\Glsxtrlong]
\cs{Glsxtrlong}\oarg{options}\marg{label}\oarg{insert}
\end{definition}

First letter upper case inline full form:
\begin{definition}[\DescribeMacro\Glsxtrfull]
\cs{Glsxtrfull}\oarg{options}\marg{label}\oarg{insert}
\end{definition}

All upper case short form:
\begin{definition}[\DescribeMacro\Glsxtrshort]
\cs{GLSxtrshort}\oarg{options}\marg{label}\oarg{insert}
\end{definition}

All upper case long form:
\begin{definition}[\DescribeMacro\Glsxtrlong]
\cs{GLSxtrlong}\oarg{options}\marg{label}\oarg{insert}
\end{definition}

All upper case inline full form:
\begin{definition}[\DescribeMacro\GLSxtrfull]
\cs{GLSxtrfull}\oarg{options}\marg{label}\oarg{insert}
\end{definition}

Plural forms are also available.

Short form plurals:
\begin{definition}[\DescribeMacro\glsxtrshortpl]
\cs{glsxtrshortpl}\oarg{options}\marg{label}\oarg{insert}
\end{definition}
\begin{definition}[\DescribeMacro\Glsxtrshortpl]
\cs{Glsxtrshortpl}\oarg{options}\marg{label}\oarg{insert}
\end{definition}
\begin{definition}[\DescribeMacro\GLSxtrshortpl]
\cs{GLSxtrshortpl}\oarg{options}\marg{label}\oarg{insert}
\end{definition}

Long form plurals:
\begin{definition}[\DescribeMacro\glsxtrlongpl]
\cs{glsxtrlongpl}\oarg{options}\marg{label}\oarg{insert}
\end{definition}
\begin{definition}[\DescribeMacro\Glsxtrlongpl]
\cs{Glsxtrlongpl}\oarg{options}\marg{label}\oarg{insert}
\end{definition}
\begin{definition}[\DescribeMacro\GLSxtrlongpl]
\cs{GLSxtrlongpl}\oarg{options}\marg{label}\oarg{insert}
\end{definition}

Full form plurals:
\begin{definition}[\DescribeMacro\glsxtrfullpl]
\cs{glsxtrfullpl}\oarg{options}\marg{label}\oarg{insert}
\end{definition}
\begin{definition}[\DescribeMacro\Glsxtrfullpl]
\cs{Glsxtrfullpl}\oarg{options}\marg{label}\oarg{insert}
\end{definition}
\begin{definition}[\DescribeMacro\GLSxtrfullpl]
\cs{GLSxtrfullpl}\oarg{options}\marg{label}\oarg{insert}
\end{definition}

\begin{important}
Be careful about using \cs{glsentryfull}, \cs{Glsentryfull},
\cs{glsentryfullpl} and \cs{Glsentryfullpl}. These commands will use
the currently applied style rather than the style in use when the
entry was defined. If you have mixed styles, you'll need to use
\ics{glsxtrfull} instead. Similarly for \cs{glsentryshort} etc.
\end{important}

\section{Shortcut Commands}
\label{sec:abbrshortcuts}

The abbreviation shortcut commands can be enabled using
the package option \pkgopt[abbreviation]{shortcuts} 
(or \pkgopt[abbr]{shortcuts}). This defines the commands listed in
\tableref{tab:abbrshortcuts}.

\begin{table}[htbp]
\caption{Abbreviation Shortcut Commands}
\label{tab:abbrshortcuts}
\centering
\begin{tabular}{ll}
\bfseries Shortcut & \bfseries Equivalent Command\\
\ics{ab} & \ics{cgls}\\
\ics{abp} & \ics{cglspl}\\
\ics{as} & \ics{glsxtrshort}\\
\ics{asp} & \ics{glsxtrshortpl}\\
\ics{al} & \ics{glsxtrlong}\\
\ics{alp} & \ics{glsxtrlongpl}\\
\ics{af} & \ics{glsxtrfull}\\
\ics{afp} & \ics{glsxtrfullpl}\\
\ics{As} & \ics{Glsxtrshort}\\
\ics{Asp} & \ics{Glsxtrshortpl}\\
\ics{Al} & \ics{Glsxtrlong}\\
\ics{Alp} & \ics{Glsxtrlongpl}\\
\ics{Af} & \ics{Glsxtrfull}\\
\ics{Afp} & \ics{Glsxtrfullpl}\\
\ics{AS} & \ics{GLSxtrshort}\\
\ics{ASP} & \ics{GLSxtrshortpl}\\
\ics{AL} & \ics{GLSxtrlong}\\
\ics{ALP} & \ics{GLSxtrlongpl}\\
\ics{AF} & \ics{GLSxtrfull}\\
\ics{AFP} & \ics{GLSxtrfullpl}\\
\ics{newabbr} & \ics{newabbreviation}
\end{tabular}
\end{table}

\section{Predefined Abbreviation Styles}
\label{sec:predefabbrvstyles}

There are two types of abbreviation styles: those that treat the
abbreviation as a regular entry (so that \ics{gls} uses
\ics{glsgenentryfmt}) and those that don't treat the abbreviation as
a regular entry (so that \ics{gls} uses \ics{glsxtrgenabbrvfmt}).

The regular entry abbreviation styles set the \catattr{regular}
attribute to \qt{true} for the category assigned to each 
abbreviation with that style. This means that on \gls{firstuse},
\ics{gls} uses the value of the \gloskey{first} field and on
subsequent use \ics{gls} uses the value of the \gloskey{text} field
(and analogously for the plural and case-changing versions). The
\gloskey{short} and \gloskey{long} fields are set as appropriate
and may be accessed through commands like \ics{glsxtrshort}. 

The other abbreviation styles don't modify the \catattr{regular}
attribute. The \gloskey{first} and \gloskey{text} fields (and their
plural forms) are set and can be accessed through commands like 
\cs{glsfirst}, but they aren't used by commands like \ics{gls},
which instead use the short form (stored in the \gloskey{short} key)
and the display full format (through commands like
\ics{glsxtrfullformat} that are defined by the style).

In both cases, the \gls{firstuse} of \ics{gls} may not match the
text produced by \ics{glsfirst} (and likewise for the plural
and case-changing versions).

\begin{important}
For the \qt{sc} styles that use \ics{textsc}, be careful about your choice
of fonts as some only have limited support. For
example, you may not be able to combine bold and small-caps. I
recommend that you at least use the \sty{fontenc} package with the
\pkgoptfmt{T1} option or something similar.
\end{important}

The \qt{sc} styles all use
\begin{definition}[\DescribeMacro\glsxtrscfont]
\cs{glsxtrscfont}\marg{text}
\end{definition}
which is defined as
\begin{verbatim}
\newcommand*{\glsxtrscfont}[1]{\textsc{#1}}
\end{verbatim}
The default plural suffix for the short form is set to
\begin{definition}[\DescribeMacro\glsxtrscsuffix]
\cs{glsxtrscsuffix}
\end{definition}
This just defined as
\begin{verbatim}
\newcommand*{\glsxtrscsuffix}{\glstextup{\glspluralsuffix}}
\end{verbatim}
The \ics{glstextup} command is provided by \sty{glossaries}
and is used to switch off the small caps font for the suffix.
If you override the default short plural using the
\gloskey{shortplural} key when you define the abbreviation
you will need to make the appropriate adjustment if necessary.
(Remember that the default plural suffix behaviour can be modified
through the use of the \catattr{aposplural} and
\catattr{noshortplural} attributes. See 
\sectionref{sec:categories} for further details.)

The \qt{sm} styles all use
\begin{definition}[\DescribeMacro\glsxtrsmfont]
\cs{glsxtrsmfont}\marg{text}
\end{definition}
This is defined as:
\begin{verbatim}
\newcommand*{\glsxtrsmfont}[1]{\textsmaller{#1}}
\end{verbatim}
If you want to use this, you must explicitly load the \sty{relsize}
package which defines the \ics{textsmaller} command. If you want to
easily switch between the \qt{sc} and \qt{sm} styles, you may find
it easier to redefine this command to convert to upper case:
\begin{verbatim}
\renewcommand*{\glsxtrsmfont}[1]{\textsmaller{\MakeTextUppercase{#1}}}
\end{verbatim}
The default plural suffix for the short form is set to
\begin{definition}[\DescribeMacro\glsxtrsmsuffix]
\cs{glsxtrsmsuffix}
\end{definition}
This just does \ics{glspluralsuffix}.

The \qt{em} styles all redefine \ics{glsabbrvfont} to use 
\ics{emph}. This is done explicitly and not through a helper
command such as \cs{glsxtrscfont}.

Some of the styles use
\begin{definition}[\DescribeMacro\glsxtrfullsep]
\cs{glsxtrfullsep}\marg{label}
\end{definition}
as a separator between the long and short forms. This is defined as
a space by default, but may be changed as required. For example:
\begin{verbatim}
\renewcommand*{\glsxtrfullsep}[1]{~}
\end{verbatim}
or
\begin{verbatim}
\renewcommand*{\glsxtrfullsep}[1]{\glsacspace{#1}}
\end{verbatim}

\subsection{Predefined Abbreviation Styles that Set the Regular
Attribute}
\label{sec:predefregabbrvstyles}

The following abbreviation styles set the \catattr{regular}
attribute to \qt{true} for all categories that have abbreviations
defined with any of these styles.

\begin{description}
\item[\abbrstyle{short}]
This only displays the short form on \gls{firstuse}. The \gloskey{name}
is set to the short form. The \gloskey{description} is set to the
long form. The inline full form displays
\meta{short} (\meta{long}). The long form on its own can be
displayed through commands like \ics{glsxtrlong}.

\item[\abbrstyle{short-sc}]
Like \abbrstyle{short} but redefines \cs{glsabbrvfont} to
use \ics{glsxtrscfont}.

\item[\abbrstyle{short-sm}]
Like \abbrstyle{short} but redefines \cs{glsabbrvfont} to
use \ics{glsxtrsmfont}.

\item[\abbrstyle{short-em}]
Like \abbrstyle{short} but redefines \cs{glsabbrvfont} to
use \ics{emph}.

\item[\abbrstyle{short-desc}]
Like the \abbrstyle{short} style, but the \gloskey{name} is set to
the full form and the \gloskey{description} must be supplied by the
user. You may prefer to use the \abbrstyle{short} style with the
post-description hook set to display the long form and override
the \gloskey{description} key. (See the sample file
\texttt{sample-acronym-desc.tex}.)

\item[\abbrstyle{short-sc-desc}]
Like \abbrstyle{short} but redefines \cs{glsabbrvfont} to
use \ics{glsxtrscfont}.

\item[\abbrstyle{short-sm-desc}]
Like \abbrstyle{short-desc} but redefines \cs{glsabbrvfont} to
use \ics{glsxtrsmfont}.

\item[\abbrstyle{short-em-desc}]
Like \abbrstyle{short-desc} but redefines \cs{glsabbrvfont} to
use \ics{emph}.

\item[\abbrstyle{long-desc}]
This style only displays the long form, regardless of first or
subsequent use of commands \ics{gls}. The short form may be 
accessed through commands like \ics{glsxtrshort}. The inline full
form displays \meta{long} (\meta{short}).

The \gloskey{name} is set to the long form and the
\gloskey{description} must be provided by the user. The predefined
glossary styles won't display the short form. You can use the
post-description hook to automatically append the short form to the
description. The inline full form will display \meta{long}
(\meta{short}).

\item[\abbrstyle{long-desc-sc}]
Like the \abbrstyle{long-desc} style but the short form (accessed
through commands like \ics{glsxtrshort}) use \ics{glsxtrscfont}.

\item[\abbrstyle{long-desc-sm}]
Like \abbrstyle{long-desc} but redefines \cs{glsabbrvfont} to
use \ics{glsxtrsmfont}.

\item[\abbrstyle{long-desc-em}]
Like \abbrstyle{long-desc} but redefines \cs{glsabbrvfont} to
use \ics{emph}.

\item[\abbrstyle{long}]
This style doesn't really make sense if you don't use the short
form anywhere in the document, but is provided for completeness.
This is like the \abbrstyle{long-desc} style, but the \gloskey{name}
is set to the short form and the \gloskey{description} is set to the
long form.

\item[\abbrstyle{long-sc}]
Like the \abbrstyle{long} style but the short form (accessed
through commands like \ics{glsxtrshort}) use \ics{glsxtrscfont}.

\item[\abbrstyle{long-sm}]
Like \abbrstyle{long} but redefines \cs{glsabbrvfont} to
use \ics{glsxtrsmfont}.

\item[\abbrstyle{long-em}]
Like \abbrstyle{long} but redefines \cs{glsabbrvfont} to
use \ics{emph}.

\end{description}

\subsection{Predefined Abbreviation Styles that Don't Set the Regular
Attribute}
\label{sec:predefnonregabbrvstyles}

The following abbreviation styles will set the 
\catattr{regular} attribute to \qt{false} if it has previously
been set. If it hasn't already been set, it's left unset.
Other attributes may also be set, depending on the style.

\begin{description}
\item[\abbrstyle{long-short}]
On \gls{firstuse}, this style uses the format \meta{long} (\meta{short}).
The inline and display full forms are the same. The \gloskey{name}
is set to the short form. The 
\gloskey{description} is set to the long form. The long and short
forms are separated by \cs{glsxtrfullsep}.

\item[\abbrstyle{long-short-sc}]
Like \abbrstyle{long-short} but redefines \cs{glsabbrvfont} to
use \ics{glsxtrscfont}.

\item[\abbrstyle{long-short-sm}]
Like \abbrstyle{long-short} but redefines \cs{glsabbrvfont} to
use \ics{glsxtrsmfont}.

\item[\abbrstyle{long-short-em}]
Like \abbrstyle{long-short} but redefines \cs{glsabbrvfont} to
use \ics{emph}.

\item[\abbrstyle{long-short-desc}]
On \gls{firstuse}, this style uses the format \meta{long} (\meta{short}).
The inline and display full forms are the same. The \gloskey{name}
is set to the full form. The 
\gloskey{description} must be supplied by the user.
The long and short forms are separated by \cs{glsxtrfullsep}.

\item[\abbrstyle{long-short-sc-desc}]
Like \abbrstyle{long-short-desc} but redefines \cs{glsabbrvfont} to
use \ics{glsxtrscfont}.

\item[\abbrstyle{long-short-sm-desc}]
Like \abbrstyle{long-short-desc} but redefines \cs{glsabbrvfont} to
use \ics{glsxtrsmfont}.

\item[\abbrstyle{long-short-em-desc}]
Like \abbrstyle{long-short-desc} but redefines \cs{glsabbrvfont} to
use \ics{emph}.

\item[\abbrstyle{short-long}]
On \gls{firstuse}, this style uses the format \meta{short} (\meta{long}).
The inline and display full forms are the same. The \gloskey{name}
is set to the short form. The 
\gloskey{description} is set to the long form.
The short and long forms are separated by \cs{glsxtrfullsep}.

\item[\abbrstyle{short-sc-long}]
Like \abbrstyle{short-long} but redefines \cs{glsabbrvfont} to
use \ics{glsxtrscfont}.

\item[\abbrstyle{short-sm-long}]
Like \abbrstyle{short-long} but redefines \cs{glsabbrvfont} to
use \ics{glsxtrsmfont}.

\item[\abbrstyle{short-em-long}]
Like \abbrstyle{short-long} but redefines \cs{glsabbrvfont} to
use \ics{emph}.

\item[\abbrstyle{short-long-desc}]
On \gls{firstuse}, this style uses the format \meta{short} (\meta{long}).
The inline and display full forms are the same. The \gloskey{name}
is set to the full form. The 
\gloskey{description} must be supplied by the user.
The short and long forms are separated by \cs{glsxtrfullsep}.

\item[\abbrstyle{short-sc-long-desc}]
Like \abbrstyle{short-long-desc} but redefines \cs{glsabbrvfont} to
use \ics{glsxtrscfont}.

\item[\abbrstyle{short-sm-long-desc}]
Like \abbrstyle{short-long-desc} but redefines \cs{glsabbrvfont} to
use \ics{glsxtrsmfont}.

\item[\abbrstyle{short-em-long-desc}]
Like \abbrstyle{short-long-desc} but redefines \cs{glsabbrvfont} to
use \ics{emph}.

\item[\abbrstyle{footnote}]
On \gls{firstuse}, this style displays the short form with the long form
as a footnote. This style automatically sets the
\catattr{nohyperfirst} attribute to \qt{true} for the supplied
category, so the \gls{firstuse} won't be hyperlinked (but the footnote
marker may be, if the \sty{hyperref} package is used).

The inline full form uses the \meta{short}
(\meta{long}) style. The \gloskey{name} is set to the short form.
The \gloskey{description} is set to the long form.

\item[\abbrstyle{footnote-sc}]
Like \abbrstyle{footnote} but redefines \cs{glsabbrvfont} to
use \ics{glsxtrscfont}.

\item[\abbrstyle{footnote-sm}]
Like \abbrstyle{footnote} but redefines \cs{glsabbrvfont} to
use \ics{glsxtrsmfont}.

\item[\abbrstyle{footnote-em}]
Like \abbrstyle{footnote} but redefines \cs{glsabbrvfont} to
use \ics{emph}.

\item[\abbrstyle{postfootnote}]
This is similar to the \abbrstyle{footnote} style but doesn't modify
the category attribute. Instead it changes \postlinkcat\ to 
insert the footnote after the
\gls{linktext} on \gls{firstuse}. This will also defer the footnote until after any
following punctuation character that's recognised by
\ics{glsxtrifnextpunc}.

The inline full form uses the \meta{short}
(\meta{long}) style. The \gloskey{name} is set to the short form.
The \gloskey{description} is set to the long form.

\item[\abbrstyle{postfootnote-sc}]
Like \abbrstyle{postfootnote} but redefines \cs{glsabbrvfont} to
use \ics{glsxtrscfont}.

\item[\abbrstyle{postfootnote-sm}]
Like \abbrstyle{postfootnote} but redefines \cs{glsabbrvfont} to
use \ics{glsxtrsmfont}.

\item[\abbrstyle{postfootnote-em}]
Like \abbrstyle{postfootnote} but redefines \cs{glsabbrvfont} to
use \ics{emph}.

\end{description}

\section{Defining New Abbreviation Styles}
\label{sec:newabbrvstyle}

New abbreviation styles may be defined using:
\begin{definition}[\DescribeMacro\newabbreviationstyle]
\cs{newabbreviationstyle}\marg{name}\marg{setup}\marg{fmts}
\end{definition}
where \meta{name} is the name of the new style (as used in the
mandatory argument of \ics{setabbreviationstyle}). This is similar
but not identical to the \sty{glossaries} package's
\ics{newacronymstyle} command.

\begin{important}
You can't use styles defined by
\cs{newacronymstyle} with \styfmt{glossaries-extra} unless you have
reverted \ics{newacronym} back to its generic definition from \sty{glossaries}
(using \ics{RestoreAcronyms}). The acronym styles from the
\sty{glossaries} package can't be used with abbreviations defined
with \cs{newabbreviation}.
\end{important}

The \meta{setup} argument deals with the way the entry is defined
and may set attributes for the given abbreviation 
category. This argument should redefine
\begin{definition}[\DescribeMacro\CustomAbbreviationFields]
\cs{CustomAbbreviationFields}
\end{definition}
to set the entry fields including the \gloskey{name} (defaults to
the short form if omitted),
\gloskey{sort}, \gloskey{first}, \gloskey{firstplural}. Other fields
may also be set, such as \gloskey{text}, \gloskey{plural} and
\gloskey{description}.

\begin{important}
\cs{CustomAbbreviationFields} is expanded by \cs{newabbreviation}
so take care to protect commands that shouldn't be expanded.
\end{important}

For example, the \abbrstyle{long-short} style has the following in
\meta{setup}:
\begin{verbatim}
  \renewcommand*{\CustomAbbreviationFields}{%
    name={\protect\glsabbrvfont{\the\glsshorttok}},
    sort={\the\glsshorttok},
    first={\protect\glsfirstlongfont{\the\glslongtok}%
     \protect\glsxtrfullsep{\the\glslabeltok}%
     (\protect\glsfirstabbrvfont{\the\glsshorttok})},%
    firstplural={\protect\glsfirstlongfont{\the\glslongpltok}%
     \protect\glsxtrfullsep{\the\glslabeltok}%
     (\protect\glsfirstabbrvfont{\the\glsshortpltok})},%
    plural={\protect\glsabbvfont{\the\glsshortpltok}},%
    description={\the\glslongtok}}%
\end{verbatim}
Note that the \gloskey{first} and \gloskey{firstplural} are
set even though they're not used by \cs{gls}.

The \meta{setup} argument may also redefine
\begin{definition}[\DescribeMacro\GlsXtrPostNewAbbreviation]
\cs{GlsXtrPostNewAbbreviation}
\end{definition}
which can be used to assign attributes. (This will automatically
be initialised to do nothing.)

For example, the \abbrstyle{footnote} includes the following in
\meta{setup}:
\begin{verbatim}
  \renewcommand*{\GlsXtrPostNewAbbreviation}{%
    \glssetattribute{\the\glslabeltok}{nohyperfirst}{true}%
    \glshasattribute{\the\glslabeltok}{regular}%
    {%
      \glssetattribute{\the\glslabeltok}{regular}{false}%
    }%
    {}%
  }%
\end{verbatim}
This sets the \catattr{nohyperfirst} attribute to \qt{true}.
It also unsets the \catattr{regular} attribute if it has
previously been set. Note that the \catattr{nohyperfirst}
attribute doesn't get unset by other styles, so take care
not to switch styles for the same category.

You can access the short, long, short plural and long plural
values through the following token registers.

Short value (defined by \sty{glossaries}):
\begin{definition}[\DescribeMacro\glsshorttok]
\cs{glsshorttok}
\end{definition}

Short plural value (defined by \styfmt{glossaries-extra}):
\begin{definition}[\DescribeMacro\glsshortpltok]
\cs{glsshortpltok}
\end{definition}
(This may be the default value or, if provided, the value provided by the user
through the \gloskey{shortplural} key in the optional argument
of \ics{newabbreviation}.)

Long value (defined by \sty{glossaries}):
\begin{definition}[\DescribeMacro\glslongtok]
\cs{glslongtok}
\end{definition}

Long plural value (defined by \styfmt{glossaries-extra}):
\begin{definition}[\DescribeMacro\glslongpltok]
\cs{glslongpltok}
\end{definition}
(This may be the default value or, if provided, the value provided by the user
through the \gloskey{longplural} key in the optional argument
of \ics{newabbreviation}.)

There are two other registers available that are defined by
\sty{glossaries}:

\begin{definition}[\DescribeMacro\glslabeltok]
\cs{glslabeltok}
\end{definition}
which contains the entry's label and
\begin{definition}[\DescribeMacro\glskeylisttok]
\cs{glskeylisttok}
\end{definition}
which contains the values provided in the optional argument
of \ics{newabbreviation}.

Remember put \cs{the} in front of the register command as in the
examples above. The category label can be access through
the command (not a register):
\begin{definition}[\DescribeMacro\glscategorylabel]
\cs{glscategorylabel}
\end{definition}
This may be used inside the definition of
\cs{GlsXtrPostNewAbbreviation}.

If you want to base a style on an existing style, you can use
\begin{definition}[\DescribeMacro\GlsXtrUseAbbrStyleSetup]
\cs{GlsXtrUseAbbrStyleSetup}\marg{name}
\end{definition}
where \meta{name} is the name of the existing style.
For example, the \abbrstyle{footnote-sc} and \abbrstyle{footnote-sm}
styles both simply use
\begin{verbatim}
\GlsXtrUseAbbrStyleSetup{footnote}
\end{verbatim}
within \meta{setup}.

The \meta{fmts} argument deals with the way the entry is displayed
in the document. This argument should redefine the following
commands:

The default suffix for the plural short form (if not overridden by
the \gloskey{shortplural} key):
\begin{definition}[\DescribeMacro\abbrvpluralsuffix]
\cs{abbrvpluralsuffix}
\end{definition}
(Note that this isn't used for the plural long form, which
just uses the regular \cs{glspluralsuffix}.)

The font used for the short form on \gls{firstuse} or in the full forms:
\begin{definition}[\DescribeMacro\glsfirstabbrvfont]
\cs{glsfirstabbrvfont}\marg{text}
\end{definition}

The font used for the short form on subsequent use or through
commands like \ics{glsxtrshort}:
\begin{definition}[\DescribeMacro\glsabbrvfont]
\cs{glsabbrvfont}\marg{text}
\end{definition}

The font used for the long form on \gls{firstuse} or in the full forms:
\begin{definition}[\DescribeMacro\glsfirstlongfont]
\cs{glsfirstlongfont}\marg{text}
\end{definition}

Display full form singular no case-change (used by \ics{gls} on
\gls{firstuse} for abbreviations without the \catattr{regular} attribute
set):
\begin{definition}[\DescribeMacro\glsxtrfullformat]
\cs{glsxtrfullformat}\marg{label}\marg{insert}
\end{definition}

Display full form singular first letter converted to upper case 
(used by \ics{Gls} on \gls{firstuse} for abbreviations without the 
\catattr{regular} attribute set):
\begin{definition}[\DescribeMacro\Glsxtrfullformat]
\cs{Glsxtrfullformat}\marg{label}\marg{insert}
\end{definition}

Display full form plural no case-change 
(used by \ics{glspl} on \gls{firstuse} for abbreviations without the 
\catattr{regular} attribute set):
\begin{definition}[\DescribeMacro\glsxtrfullplformat]
\cs{glsxtrfullplformat}\marg{label}\marg{insert}
\end{definition}

Display full form plural first letter converted to upper case
(used by \ics{Glspl} on \gls{firstuse} for abbreviations without the 
\catattr{regular} attribute set):
\begin{definition}[\DescribeMacro\Glsxtrfullplformat]
\cs{Glsxtrfullplformat}\marg{label}\marg{insert}
\end{definition}

In addition \meta{fmts} may also redefine the following commands that 
govern the inline full formats. If the style doesn't redefine them,
they will default to the same as the display full forms.

Inline singular no case-change (used by 
\ics{glsentryfull}, \ics{glsxtrfull} and \ics{GLSxtrfull}):
\begin{definition}[\DescribeMacro\glsxtrinlinefullformat]
\cs{glsxtrinlinefullformat}\marg{label}\marg{insert}
\end{definition}

Inline singular first letter converted to upper case (used by 
\ics{Glsentryfull} and \ics{Glsxtrfull}):
\begin{definition}[\DescribeMacro\Glsxtrinlinefullformat]
\cs{Glsxtrinlinefullformat}\marg{label}\marg{insert}
\end{definition}

Inline plural no case-change (used by 
\ics{glsentryfullpl}, \ics{glsxtrfullpl} and \ics{GLSxtrfullpl}):
\begin{definition}[\DescribeMacro\glsxtrinlinefullplformat]
\cs{glsxtrinlinefullplformat}\marg{label}\marg{insert}
\end{definition}

Inline plural first letter converted to upper case (used by 
\ics{Glsentryfullpl} and \ics{Glsxtrfullpl}):
\begin{definition}[\DescribeMacro\Glsxtrinlinefullplformat]
\cs{Glsxtrinlinefullplformat}\marg{label}\marg{insert}
\end{definition}

If you want to provide support for \sty{glossaries-accsupp}
use the following \cs{glsaccess\meta{xxx}} commands
(\sectionref{sec:accsupp}) within the definitions of
\cs{glsxtrfullformat} etc instead of the analogous
\cs{glsentry}\meta{xxx} commands. (If you don't use
\sty{glossaries-accsupp}, they will just do the corresponding
\cs{glsentry}\meta{xxx} command.)

For example, the \abbrstyle{short-long} style has the following in
\meta{fmts}:
\begin{verbatim}
  \renewcommand*{\abbrvpluralsuffix}{\glspluralsuffix}%
  \renewcommand*{\glsabbrvfont}[1]{\glsabbrvdefaultfont{##1}}%
  \renewcommand*{\glsfirstabbrvfont}[1]{\glsfirstabbrvdefaultfont{##1}}%
  \renewcommand*{\glsfirstlongfont}[1]{\glsfirstlongdefaultfont{##1}}%
  \renewcommand*{\glsxtrfullformat}[2]{%
    \glsfirstabbrvfont{\glsaccessshort{##1}}##2\glsxtrfullsep{##1}%
    (\glsfirstlongfont{\glsaccesslong{##1}})%
  }%
  \renewcommand*{\glsxtrfullplformat}[2]{%
    \glsfirstabbrvfont{\glsaccessshortpl{##1}}##2\glsxtrfullsep{##1}%
    (\glsfirstlongfont{\glsaccesslongpl{##1}})%
  }%
  \renewcommand*{\Glsxtrfullformat}[2]{%
    \glsfirstabbrvfont{\Glsaccessshort{##1}}##2\glsxtrfullsep{##1}%
    (\glsfirstlongfont{\glsaccesslong{##1}})%
  }%
  \renewcommand*{\Glsxtrfullplformat}[2]{%
    \glsfirstabbrvfont{\Glsaccessshortpl{##1}}##2\glsxtrfullsep{##1}%
    (\glsfirstlongfont{\glsaccesslongpl{##1}})%
  }%
\end{verbatim}
Since the inline full commands aren't redefined, they default
to the same as the display versions.

If you want to base a style on an existing style, you can use
\begin{definition}[\DescribeMacro\GlsXtrUseAbbrStyleFmts]
\cs{GlsXtrUseAbbrStyleFmts}\marg{name}
\end{definition}
within \meta{fmts}, where \meta{name} is the name of the existing
style. For example, the \abbrstyle{short-sc-long} style has the
following in \meta{fmts}:
\begin{verbatim}
  \GlsXtrUseAbbrStyleFmts{short-long}%
  \renewcommand*{\abbrvpluralsuffix}{\protect\glsxtrscsuffix}%
  \renewcommand*{\glsabbrvfont}[1]{\glsxtrscfont{##1}}%
\end{verbatim}
and the \abbrstyle{short-sm-long} style has:
\begin{verbatim}
  \GlsXtrUseAbbrStyleFmts{short-long-desc}%
  \renewcommand*{\glsabbrvfont}[1]{\glsxtrsmfont{##1}}%
  \renewcommand*{\abbrvpluralsuffix}{\protect\glsxtrsmsuffix}%
\end{verbatim}

The simplest examples of creating a new style based on an
existing style are the \qt{em} styles, such as the
\abbrstyle{short-em-long} style, which is defined as:
\begin{verbatim}
\newabbreviationstyle
{short-em-long}% label
{% setup
  \GlsXtrUseAbbrStyleSetup{short-long}%
}%
{% fmts
  \GlsXtrUseAbbrStyleFmts{short-long}%
  \renewcommand*{\glsabbrvfont}[1]{\emph{##1}}%
}
\end{verbatim}

\chapter{Entries in Sectioning Titles, Headers and Contents}
\label{sec:headtitle}

The \sty{glossaries} user manual cautions against using commands
like \cs{gls} in chapter or section titles. The principle problems
are:
\begin{itemize}
\item if you have a table of contents, the \gls{firstuseflag} 
will be unset in the contents rather than later in the document;
\item if you have the location lists displayed in the glossary,
unwanted locations will be added to it corresponding to the table of
contents (if present) and every page that contains the entry in the
page header (if the page style in use adds the chapter or section
title to the header);
\item if the page style in use adds the chapter or section title to
the header and attempts to convert it to upper case, the entry label
(in the argument of \cs{gls} etc) will be converted to upper case
and the entry won't be recognised;
\item if you use \sty{hyperref}, commands like \cs{gls} can't be
expanded to a simple string and only the label will appear in the
PDF bookmark (with a warning from \sty{hyperref});
\item if you use \sty{hyperref}, you will end up with nested hyperlinks
in the table of contents.
\end{itemize}

To get around all these problems, the \sty{glossaries} user manual
recommends using the expandable non-hyperlink commands, like 
\ics{glsentrytext} (for regular entries) or \ics{glsentryshort}
(for abbreviations). This is the simplest solution, but doesn't
allow for special formatting that's applied to the entry through
commands like \cs{glstext} or \cs{glsxtrshort}. This means that if,
for example, you are using one of the abbreviation styles that uses
\ics{textsc} then the short form displayed with \cs{glsentryshort} won't use small
caps. If you only have one abbreviation style in use, you can
explicitly enclose \cs{glsentryshort}\marg{label} in the argument of
\cs{glsabbrvfont}, like this:
\begin{verbatim}
\chapter{A Chapter about \glsabbrvfont{\glsentryshort{html}}}
\end{verbatim}
Or, if you are using \sty{hyperref}:
\begin{verbatim}
\chapter{A Chapter about 
\texorpdfstring{\glsabbrvfont{\glsentryshort{html}}}{\glsentryshort{html}}}
\end{verbatim}

Since this is a bit cumbersome, you might want to define a new
command to do this for you. However, if you have mixed styles this
won't work as commands like \cs{gls} and \cs{glsxtrshort} redefine
\cs{glsabbrvfont} to match the entry's style before displaying it.
In this case, the above example doesn't take into account the
shifting definitions of \cs{glsabbrvfont} and will use whatever
happens to be the last abbreviation style in use. More complicated
solutions interfere with the upper casing used by the standard
page styles that display the chapter or section title in the page
header using \ics{MakeUppercase}.

The \styfmt{glossaries-extra} package tries to resolve this by
modifying \ics{markright} and \ics{markboth}. If you don't like this
change, you can restore their former definitions using
\begin{definition}[\DescribeMacro\glsxtrRevertMarks]
\cs{glsxtrRevertMarks}
\end{definition}
In this case, you'll have to use the \sty{glossaries} manual's
recommendations of either simply using \cs{glsentryshort} (as above)
or use the sectioning command's option argument to provide an
alternative for the table of contents and page header. For example:
\begin{verbatim}
\chapter[A Chapter about \glsentryshort{html}]{A Chapter about 
\gls{html}}
\end{verbatim}

If you don't revert the mark commands back with
\cs{glsxtrRevertMarks}, you can use the commands described below in
the argument of sectioning commands. You can still use them even
if the mark commands have been reverted, but only where they don't
conflict with the page style.

The commands listed below all use \ics{texorpdfstring} if
\sty{hyperref} has been loaded so that the expandable non-formatted
version is added to the PDF bookmarks. Note that since the commands
that convert the first letter to upper case aren't expandable, the
non-case-changing version is used for the bookmarks.

These commands essentially behave as though you have used
\cs{glsxtrshort} (or equivalent) with the options
\gloskey[glslink]{noindex} and \gloskey[glslink]{hyper=false}.
The text produced won't be converted to upper case in the page
headings by default. If you want the text converted to upper case
you need to set the \catattr{headuc} attribute to \qt{true}
for the appropriate category.

\begin{important}
If you use one of the \ics{textsc} styles, be aware that the default
fonts don't provide bold small-caps or italic small-caps. This
means that if the chapter or section title style uses bold, this
may override the small-caps setting, in which case the abbreviation
will just appear as lower case bold. If the heading style uses
italic, the abbreviation may appear in upright small-caps,
\emph{even if you have set the \catattr{headuc} attribute} since
the all-capitals form still uses \cs{glsabbrvfont}.
You may want to consider using the \sty{slantsc} package in this
case.
\end{important}

Display the short form:
\begin{definition}[\DescribeMacro\glsfmtshort]
\cs{glsfmtshort}\marg{label}
\end{definition}

Display the plural short form:
\begin{definition}[\DescribeMacro\glsfmtshortpl]
\cs{glsfmtshortpl}\marg{label}
\end{definition}

First letter upper case singular short form:
\begin{definition}[\DescribeMacro\Glsfmtshort]
\cs{Glsfmtshort}\marg{label}
\end{definition}
(No case-change applied to PDF bookmarks.)

First letter upper case plural short form:
\begin{definition}[\DescribeMacro\Glsfmtshortpl]
\cs{Glsfmtshortpl}\marg{label}
\end{definition}
(No case-change applied to PDF bookmarks.)

There are also equivalent commands for the value of the
\gloskey{text} field:
\begin{definition}[\DescribeMacro\glsfmttext]
\cs{glsfmttext}\marg{label}
\end{definition}

First letter converted to upper case:
\begin{definition}[\DescribeMacro\Glsfmttext]
\cs{Glsfmttext}\marg{label}
\end{definition}
(No case-change applied to PDF bookmarks.)

The plural equivalents:
\begin{definition}[\DescribeMacro\glsfmtplural]
\cs{glsfmtplural}\marg{label}
\end{definition}
and
\begin{definition}[\DescribeMacro\Glsfmtplural]
\cs{Glsfmtplural}\marg{label}
\end{definition}

Similarly for the value of the
\gloskey{first} field:
\begin{definition}[\DescribeMacro\glsfmtfirst]
\cs{glsfmtfirst}\marg{label}
\end{definition}

First letter converted to upper case:
\begin{definition}[\DescribeMacro\Glsfmtfirst]
\cs{Glsfmtfirst}\marg{label}
\end{definition}
(No case-change applied to PDF bookmarks.)

The plural equivalents:
\begin{definition}[\DescribeMacro\glsfmtfirstpl]
\cs{glsfmtfirstpl}\marg{label}
\end{definition}
and
\begin{definition}[\DescribeMacro\Glsfmtfirstpl]
\cs{Glsfmtfirstpl}\marg{label}
\end{definition}

\chapter{Categories}
\label{sec:categories}

Each entry defined by \cs{newglossaryentry} (or commands that
internally use \cs{newglossaryentry} such as \cs{newabbreviation}) 
is assigned a category
through the \gloskey{category} key. You may add any category that
you like, but since the category is a label used in the creation
of some control sequences, avoid problematic characters within the
category label. (So take care if you have \sty{babel} shorthands on
that make some characters active.)

The use of categories can give you more control over the way entries
are displayed in the text or glossary.

The default category assumed by
\cs{newglossaryentry} is labelled \category{general}. Abbreviations
defined with \cs{newabbreviation} have the category set to
\category{abbreviation} by default. Abbreviations defined with
\cs{newacronym} have the category set to \category{acronym} by
default.

Additionally, if you have enabled \ics{newterm} with the
\pkgopt{index} package option that command
will set the category to \category{index} by default. If you have
enabled \ics{glsxtrnewsymbol} with the \pkgopt{symbols} package
option, that command will set the category to \category{symbol}. If you have
enabled \ics{glsxtrnewnumber} with the \pkgopt{numbers} package
option, that command will set the category to \category{number}.

You can obtain the category label for a given entry using
\begin{definition}[\DescribeMacro\glscategory]
\cs{glscategory}\marg{label}
\end{definition}
This is equivalent to commands like \cs{glsentryname} and so may be
used in an expandable context. No error is generated if the entry
doesn't exist.

You can test the category for a given entry using
\begin{definition}[\DescribeMacro\glsifcategory]
\cs{glsifcategory}\marg{entry-label}\marg{category-label}\marg{true
part}\marg{false part}
\end{definition}
This is equivalent to
\begin{alltt}
\ics{ifglsfieldeq}\marg{entry-label}\{category\}\marg{category-label}\marg{true
part}\marg{false part}
\end{alltt}
so any restrictions that apply to \cs{ifglsfieldeq} also apply to
\cs{glsifcategory}.

Each category may have a set of attributes. For example, the
\category{general} and \category{acronym} categories have the
attribute \catattr{regular} set to \qt{true} to indicate that all
entries with either of those categories are regular entries (as
opposed to abbreviations). This attribute is accessed by
\cs{glsentryfmt} to determine whether to use \cs{glsgenentryfmt} or
\cs{glsxtrgenabbrvfmt}.

Other attributes recognised by \styfmt{glossaries-extra} are:

\begin{description}

\item[\catattr{nohyperfirst}] When using commands like \ics{gls}
this will automatically suppress the hyperlink on \gls{firstuse} for entries with a
category that has this attribute set to \qt{true}.
(This settings can be overridden by explicitly setting
the \gloskey[glslink]{hyper} key on or off in the optional argument of
commands like \cs{gls}.)

\item[\catattr{nohyper}] When using commands like \ics{gls}
this will automatically suppress the hyperlink for entries with a
category that has this attribute set to \qt{true}.
(This settings can be overridden by explicitly setting
the \gloskey[glslink]{hyper} key on or off in the optional argument of
commands like \cs{gls}.)

\item[\catattr{indexonlyfirst}] This is similar to the 
\pkgopt{indexonlyfirst} package option but only for entries
that have a category with this attribute set to \qt{true}.

\item[\catattr{discardperiod}] If set to \qt{true}, the
post-\gls{linktext} hook will
discard a~full stop (period) that follows \emph{non-plural} commands like \cs{gls} or
\cs{glstext}. (Provided for entries such as abbreviations that end with a full stop.)

\item[\catattr{pluraldiscardperiod}] If this attribute is set to 
\qt{true} \emph{and} the \catattr{discardperiod} attribute is set to
\qt{true}, this will behave as above for the plural commands like
\cs{glspl} or \cs{glsplural}.

\item[\catattr{retainfirstuseperiod}] If this attribute is set
to \qt{true} then the full stop won't be discarded for
\gls{firstuse} instances, even if \catattr{discardperiod} or
\catattr{pluraldiscardperiod} are set. This is useful for
\meta{short} (\meta{long}) abbreviation styles where only the short
form has a trailing full stop..

\item[\catattr{insertdots}] If this attribute is set to \qt{true}
any entry defined using \ics{newabbreviation} will automatically
have full stops (periods) inserted after each letter. The entry will
be defined with those dots present as though they had been present
in the \meta{short} argument of \cs{newabbreviation} (rather than
inserting them every time the entry is used). The short plural
form defaults to the new dotted version of the original \meta{short}
form with the plural suffix appended.

\begin{important}
If you explicitly override
the short plural using the \gloskey{shortplural} key, you must
explicitly insert the dots yourself (since there's no way for the
code to determine if the plural has a suffix that shouldn't be
followed by a dot).
\end{important}

This attribute is best used with the \catattr{discardperiod}
attribute set to \qt{true}.

\item[\catattr{aposplural}] If this attribute is set to \qt{true},
\ics{newabbreviation} will insert an apostrophe (') before
the plural suffix for the \emph{short} plural form (unless explicitly
overridden with the \gloskey{shortplural} key). The long plural form
is unaffected by this setting.

\item[\catattr{noshortplural}] If this attribute is set to
\qt{true}, \ics{newabbreviation} won't append the plural suffix for
the short plural form. This means the \gloskey{short} and
\gloskey{shortplural} values will be the same unless explicitly
overridden. \emph{The \catattr{aposplural} attribute trumps
the \catattr{noshortplural} attribute.}

\item[\catattr{headuc}] If this attribute is set to \qt{true},
commands like \ics{glsfmtshort} will use the upper case version
in the page headers.

\item[\catattr{tagging}] If this attribute is set to \qt{true},
the tagging command defined by \ics{GlsXtrEnableInitialTagging}
will be activated to use \ics{glsxtrtagfont} in the glossary
(see \sectionref{sec:tagging}).

\item[\catattr{entrycount}] Unlike the above attributes,
this attribute isn't boolean but instead must be an integer 
value and is used in combination with \ics{glsenableentrycount}
(see \sectionref{sec:entrycountmods}). Leave blank or undefined
for categories that shouldn't have this facility enabled. The
value of this attribute is used by \ics{glsxtrifcounttrigger}
to determine how commands such as \ics{cgls} should behave.

With \sty{glossaries}, commands like \cs{cgls} use \cs{cglsformat}
only if the previous usage count for that entry was equal to~1.
With \styfmt{glossaries-extra} the test is now for entries that
have the \catattr{entrycount} attribute set and
where the previous usage count for that entry is less than or
equal to the value of that attribute.

\item[\catattr{glossdesc}] The \ics{glossentrydesc} command
(used in the predefined glossary styles) is modified by
\styfmt{glossaries-extra} to check for this attribute.
If the attribute is set to \qt{firstuc}, the first letter 
of the description will be converted to upper case (using 
\ics{Glsentrydesc}). If the attribute is set to \qt{title},
the title casing command \ics{capitalisewords} (provided
by \sty{mfirstuc}) is used on the name. Any other values of
this attribute are ignored.

\item[\catattr{glossname}] As \catattr{glossdesc} but applies
to \ics{glossentryname}. Additionally, if this attribute is
set to \qt{uc} the name is converted to all capitals.

\item[\catattr{indexname}] If set, the \cs{glsxtrpostnamehook} hook
used at the end of \ics{glossentyname}
will index the entry using \ics{index}. See
\sectionref{sec:autoindex} for further details.

\item[\catattr{dualindex}] If set, whenever a glossary entry
has information written to the external glossary file
through commands like \ics{gls} and \ics{glsadd}, a~corresponding
line will be written to the indexing file using \ics{index}. See
\sectionref{sec:autoindex} for further details.

\end{description}

An attribute can be set using:
\begin{definition}[\DescribeMacro\glssetcategoryattribute]
\cs{glssetcategoryattribute}\marg{category-label}\marg{attribute-label}\marg{value}
\end{definition}
where \meta{category-label} is the category label,
\meta{attribute-label} is the attribute label and \meta{value} is
the new value for the attribute.

There is a shortcut version to set the \catattr{regular} attribute
to \qt{true}:
\begin{definition}[\DescribeMacro\glssetregularcategory]
\cs{glssetregularcategory}\marg{category-label}
\end{definition}

If you need to lookup the category label for a particular entry, you
can use the shortcut command:
\begin{definition}[\DescribeMacro\glssetattribute]
\cs{glssetattribute}\marg{entry-label}\marg{attribute-label}\marg{value}
\end{definition}
This uses \cs{glssetcategoryattribute} with \cs{glscategory} to set
the attribute. Note that this will affect all other entries that
share this entry's category.

You can fetch the value of an attribute for a particular category
using:
\begin{definition}[\DescribeMacro\glsgetcategoryattribute]
\cs{glsgetcategoryattribute}\marg{category-label}\marg{attribute-label}
\end{definition}
Again there is a shortcut if you need to lookup the category label
for a given entry:
\begin{definition}[\DescribeMacro\glsgetattribute]
\cs{glsgetattribute}\marg{entry-label}\marg{attribute-label}
\end{definition}

You can test if an attribute has been assigned to a given
category using:
\begin{definition}[\DescribeMacro\glshascategoryattribute]
\cs{glshascategoryattribute}\marg{category-label}\marg{attribute-label}\marg{true
code}\marg{false code}
\end{definition}
This uses \sty{etoolbox}'s 
\cs{ifcsvoid} and does \meta{true code} if the attribute has been
set and isn't blank and isn't \cs{relax}. The shortcut if you need
to lookup the category label from an entry is:
\begin{definition}[\DescribeMacro\glshasattribute]
\cs{glshasattribute}\marg{entry-label}\marg{attribute-label}\marg{true
code}\marg{false code}
\end{definition}

You can test the value of an attribute for a particular category
using:
\begin{definition}[\DescribeMacro\glsifcategoryattribute]
\cs{glsifcategoryattribute}\marg{category-label}\marg{attribute-label}\marg{value} \marg{true-part}\marg{false-part}
\end{definition}
This tests if the attribute (given by \meta{attribute-label}) for
the category (given by \meta{category-label}) is set and equal to
\meta{value}. If true, \meta{true-part} is done. If the attribute
isn't set or is set but isn't equal to \meta{value}, \meta{false
part} is done.

For example:
\begin{verbatim}
\glsifcategoryattribute{general}{nohyper}{true}{NO HYPER}{HYPER}
\end{verbatim}
This does \qt{NO HYPER} if the \category{general} category has the
\catattr{nohyper} attribute set to \texttt{true} otherwise if
does \qt{HYPER}.

With boolean-style attributes like \catattr{nohyper}, make sure you
always test for \texttt{true} not \texttt{false} in case the attribute hasn't been set.

Again there's a shortcut if you need to lookup the category label
from a particular entry:
\begin{definition}[\DescribeMacro\glsifattribute]
\cs{glsifattribute}\marg{entry-label}\marg{attribute-label}\marg{value}\marg{true-part} \marg{false-part}
\end{definition}

There's also a shortcut to determine if a particular category has
the \catattr{regular} attribute set:
\begin{definition}[\DescribeMacro\glsifregularcategory]
\cs{glsifregularcategory}\marg{category-label}\marg{true-part}\marg{false-part}
\end{definition}
Alternatively, if you need to lookup the category for a particular
entry:
\begin{definition}[\DescribeMacro\glsifregular]
\cs{glsifregular}\marg{entry-label}\marg{true-part}\marg{false-part}
\end{definition}

You can iterate through all entries with a given category using:
\begin{definition}
\cs{glsforeachincategory}\oarg{glossary-labels}\marg{category-label} \marg{glossary-cs}\marg{label-cs}\marg{body}
\end{definition}
This iterates through all entries in the glossaries identified by
the comma-separated list \meta{glossary-labels} that have the
category given by \meta{category-label} and performs \meta{body} for
each match. Within \meta{body}, you can use \meta{glossary-cs} and
\meta{label-cs}
(which much be control sequences) to access the current glossary and
entry label. If \meta{glossary-labels} is omitted, all glossaries
are assumed.

Similarly, you can iterate through all entries that have a category
with a given attribute using:
\begin{definition}[\DescribeMacro\glsforeachwithattribute]
\cs{glsforeachwithattribute}\oarg{glossary-labels}\marg{attribute-label} \marg{attribute-value}\marg{glossary-cs}\marg{label-cs}\marg{body}
\end{definition}
This will do \meta{body} for each entry that has a category with the
attribute \meta{attribute-label} set to \meta{attribute-value}.
The remaining arguments are as the previous command.

You can change the category for a particular entry using the
standard glossary field changing commands, such as
\ics{glsfielddef}. Alternatively, you can use
\begin{definition}[\DescribeMacro\glsxtrsetcategory]
\cs{glsxtrsetcategory}\marg{entry-labels}\marg{category-label}
\end{definition}
This will change the category to \meta{category-label} for each
entry listed in the comma-separated list \meta{entry-labels}. This
command uses \ics{glsfieldxdef} so it will expand
\meta{category-label} and make the change global.

You can also change the category for all entries with a glossary or
glossaries using:
\begin{definition}[\DescribeMacro\glsxtrsetcategoryforall]
\cs{glsxtrsetcategoryforall}\marg{glossary-labels}\marg{category-label}
\end{definition}
where \meta{glossary-labels} is a comma-separated list of glossary
labels.

\chapter{Entry Counting}
\label{sec:entrycount}

As mentioned in \sectionref{sec:entrycountmods},
\styfmt{glossaries-extra} modifies the \ics{glsenableentrycount} command to allow
for the \catattr{entrycount} attribute. This means that
you not only need to enable entry counting with
\ics{glsenableentrycount}, but you also need
to set the appropriate attribute (see \sectionref{sec:categories}).

You may now use \ics{cgls} instead of \ics{gls} even if
you haven't enabled entry counting. You will only get a warning 
if you use \cs{glsenableentrycount} without setting the 
\catattr{entrycount} attribute.
(With \sty{glossaries}, commands like \ics{cgls} will generate
a warning if \cs{glsenableentrycount} hasn't been used.)
The abbreviation shortcut \ics{ab} uses \cs{cgls} 
(see \sectionref{sec:abbrshortcuts}) unlike the acronym shortcut
\ics{ac} which uses \cs{gls}.

All upper case versions (not provided by \sty{glossaries}) are
also available:
\begin{definition}[\DescribeMacro\cGLS]
\cs{cGLS}\oarg{options}\marg{label}\oarg{insert}
\end{definition}
and
\begin{definition}[\DescribeMacro\cGLSpl]
\cs{cGLSpl}\oarg{options}\marg{label}\oarg{insert}
\end{definition}
These are analogous to \cs{cgls} and \cs{cglspl} but they
use
\begin{definition}[\DescribeMacro\cGLSformat]
\cs{cGLSformat}\marg{label}\marg{insert}
\end{definition}
and
\begin{definition}[\DescribeMacro\cGLSplformat]
\cs{cGLSplformat}\marg{label}\marg{insert}
\end{definition}
which convert the analogous \cs{cglsformat} and
\cs{cglsplformat} to upper case.

[TODO: work out what to do about other commands such
as \verb|\glsdisp| and \verb|\glstext|.]

Just using \sty{glossaries}:
\begin{verbatim}
\documentclass{article}

\usepackage{glossaries}

\makeglossaries

\glsenableentrycount

\newacronym{html}{HTML}{hypertext markup language}
\newacronym{xml}{XML}{extensible markup language}

\begin{document}

Used once: \cgls{html}.

Used twice: \cgls{xml} and \cgls{xml}.

\printglossaries

\end{document}
\end{verbatim}

If you switch to \styfmt{glossaries-extra} you must set the
\catattr{entrycount} attribute:
\begin{verbatim}
\documentclass{article}

\usepackage{glossaries-extra}

\makeglossaries

\glsenableentrycount

\glssetcategoryattribute{abbreviation}{entrycount}{1}

\newabbreviation{html}{HTML}{hypertext markup language}
\newabbreviation{xml}{XML}{extensible markup language}

\begin{document}

Used once: \cgls{html}.

Used twice: \cgls{xml} and \cgls{xml}.

\printglossaries

\end{document}
\end{verbatim}

When activated with \cs{glsenableentrycount}, commands such as 
\ics{cgls} now use
\begin{definition}[\DescribeMacro\glsxtrifcounttrigger]
\cs{glsxtrifcounttrigger}\marg{label}\marg{trigger code}\marg{normal
code}
\end{definition}
to determine if the entry trips the entry count trigger.
The \meta{trigger code} uses commands like \cs{cglsformat} and 
unsets the \gls{firstuseflag}. The \meta{normal code} is the code that
would ordinarily be performed by whatever the equivalent
command is (for example, \cs{cgls} will use \cs{cglsformat} in 
\meta{trigger code} but the usual \cs{gls} behaviour in \meta{normal
code}).

The default definition is:
\begin{verbatim}
\newcommand*{\glsxtrifcounttrigger}[3]{%
 \glshasattribute{#1}{entrycount}%
 {%
   \ifnum\glsentryprevcount{#1}>\glsgetattribute{#1}{entrycount}\relax
    #3%
   \else
    #2%
   \fi 
 }%
 {#3}% 
}
\end{verbatim}
This means that if an entry is assigned to a category that has
the \catattr{entrycount} attribute then the \meta{trigger code}
will be used if the previous count value 
(the number of times the entry was used on the last run) is greater
than the value of the attribute.

For example, to trigger normal use if the previous count value
is greater than four:
\begin{verbatim}
\glssetcategoryattribute{abbreviation}{entrycount}{4}
\end{verbatim}

There is a convenient command provided to enable entry counting,
set the \catattr{entrycount} attribute and redefine \ics{gls},
etc to use \ics{cgls} etc:
\begin{definition}[\DescribeMacro\GlsXtrEnableEntryCounting]
\cs{GlsXtrEnableEntryCounting}\marg{categories}\marg{value}
\end{definition}
The first argument \meta{categories} is a comma-separated list
of categories. For each category, the \catattr{entrycount}
attribute is set to \meta{value}. In addition, this does:
\begin{verbatim}
\renewcommand*{\gls}{\cgls}%
\renewcommand*{\Gls}{\cGls}%
\renewcommand*{\glspl}{\cglspl}%
\renewcommand*{\Glspl}{\cGlspl}%
\renewcommand*{\GLS}{\cGLS}%
\renewcommand*{\GLSpl}{\cGLSpl}%
\end{verbatim}
This makes it easier to enable entry-counting on existing
documents.

If you use \cs{GlsXtrEnableEntryCounting} more than once, subsequent uses will
just set the \catattr{entrycount} attribute for each listed
category.

The above example document can then become:
\begin{verbatim}
\documentclass{article}

\usepackage{glossaries-extra}

\makeglossaries

\GlsXtrEnableEntryCounting{abbreviation}{1}

\newabbreviation{html}{HTML}{hypertext markup language}
\newabbreviation{xml}{XML}{extensible markup language}

\begin{document}

Used once: \gls{html}.

Used twice: \gls{xml} and \gls{xml}.

\printglossaries

\end{document}
\end{verbatim}

The standard entry-counting function describe above counts
the number of times an entry has been marked as used throughout
the document. (The reset commands will reset the total back to 
zero.) If you prefer to count per sectional-unit, you can
use
\begin{definition}[\DescribeMacro\GlsXtrEnableEntryUnitCounting]
\cs{GlsXtrEnableEntryUnitCounting}\marg{categories}\marg{value}\marg{counter-name}
\end{definition}
where \meta{categories} is a comma-separated list of categories
to which this feature should be applied, \meta{value} is the
trigger value and \meta{counter-name} is the name of the counter
used by the sectional unit.

\begin{important}
Due to the asynchronous nature of \TeX's output routine,
discrepancies will occur in page spanning paragraphs if you
use the \ctr{page} counter.
\end{important}

Note that you can't use both the document-wide counting and
the per-unit counting in the same document.

The counter value is used as part of a label, which means
that \cs{the}\meta{counter-name} needs to be expandable.
Since \sty{hyperref} also has a similar requirement and provides
\cs{theH}\meta{counter-name} as an expandable alternative,
\styfmt{glossaries-extra} will use \cs{theH}\meta{counter-name}
if it exists otherwise it will use \cs{the}\meta{counter-name}.

The per-unit counting function uses two attributes: \catattr{entrycount}
(as before) and \catattr{unitcount} (the name of the counter).

Both the original document-wide counting mechanism and the
per-unit counting mechanism provide a command that can be
used to access the current count value for this run:
\begin{definition}[\DescribeMacro\glsentrycurrcount]
\cs{glsentrycurrcount}\marg{label}
\end{definition}
and the final value from the previous run:
\begin{definition}[\DescribeMacro\glsentryprevcount]
\cs{glsentryprevcount}\marg{label}
\end{definition}
In the case of the per-unit counting, this is the final value
\emph{for the current unit}. In both commands \meta{label}
is the entry's label.

The per-unit counting mechanism additionally provides:
\begin{definition}[\DescribeMacro\glsentryprevtotalcount]
\cs{glsentryprevtotalcount}\marg{label}
\end{definition}
which gives the sum of all the per-unit totals from the previous run
for the entry given by \meta{label}, and
\begin{definition}[\DescribeMacro\glsentryprevmaxcount]
\cs{glsentryprevmaxcount}\marg{label}
\end{definition}
which gives the maximum per-unit total from the previous run.

The above two commands are unavailable for the document-wide counting.

Example of per-unit counting, where the unit is the chapter:
\begin{verbatim}
\documentclass{report}
\usepackage{glossaries-extra}

\GlsXtrEnableEntryUnitCounting{abbreviation}{2}{chapter}

\makeglossaries

\newabbreviation{html}{HTML}{hypertext markup language}
\newabbreviation{css}{CSS}{cascading style sheet}

\newglossaryentry{sample}{name={sample},description={sample}}

\begin{document}
\chapter{Sample}

Used once: \gls{html}.

Used three times: \gls{css} and \gls{css} and \gls{css}.

Used once: \gls{sample}.

\chapter{Another Sample}

Used once: \gls{css}.

Used twice: \gls{html} and \gls{html}.

\printglossaries
\end{document}
\end{verbatim}
In this document, the \texttt{css} entry is used three times in the
first chapter. This is more than the trigger value of 2, so
\verb|\gls{css}| is expanded on \gls{firstuse} with the short
form used on subsequent use, and the \texttt{css} entries in
that chapter are added to the glossary. In the second chapter,
the \texttt{css} entry is only used once, which trips the 
suppression trigger, so in that chapter, the long form
is used and \verb|\gls{css}| doesn't get a line added to
the glossary file.

The \texttt{html} is used a total of three times, but the
expansion and indexing suppression trigger is tripped 
in both chapters because the per-unit total (1 for the first
chapter and 2 for the second chapter) is less than or equal
to the trigger value.

The \texttt{sample} entry has only been used once, but it doesn't
trip the indexing suppression because it's in the \category{general}
category, which hasn't been listed in
\cs{GlsXtrEnableEntryUnitCounting}.

The per-unit entry counting can be used for other purposes.
In the following example document the trigger value is set
to zero, which means the index suppression won't be triggered,
but the unit entry count is used to automatically suppress the
hyperlink for commands like \ics{gls} by modifying the
hook
\begin{definition}[\DescribeMacro\glslinkcheckfirsthyperhook]
\cs{glslinkcheckfirsthyperhook}
\end{definition}
which is used at the end of the macro the determines whether
or not to suppress the hyperlink.

\begin{verbatim}
\documentclass{article}

\usepackage[colorlinks]{hyperref}
\usepackage{glossaries-extra}

\makeglossaries

\GlsXtrEnableEntryUnitCounting{general}{0}{page}

\newglossaryentry{sample}{name={sample},description={an example}}

\renewcommand*{\glslinkcheckfirsthyperhook}{%
  \ifnum\glsentrycurrcount\glslabel>0
   \setkeys{glslink}{hyper=false}%
  \fi
}

\begin{document}

A \gls{sample} entry.
Next use: \gls{sample}.

\newpage

Next page: \gls{sample}.
Again: \gls{sample}.

\printglossaries

\end{document}
\end{verbatim}
This only produces a hyperlink for the first instance of 
\verb|\gls{sample}| on each page.

The earlier warning about using the \ctr{page} counter still 
applies. If the first instance of \cs{gls} occurs at the top of the
page within a paragraph that started on the previous page, then
the count will continue from the previous page.

\chapter{Auto-Indexing}
\label{sec:autoindex}

It's possible that you may also want a normal index as well as
the glossary, and you may want entries to automatically be
added to the index (as in this document).
There are two attributes that govern this: \catattr{indexname}
and \catattr{dualindex}.

The \ics{glsxtrpostnamehook} macro, used
at the end of \ics{glossentryname} and \ics{Glossentryname},
checks the \catattr{indexname} attribute for the category
associated with that entry.
Since \cs{glossentryname} is used in the default glossary
styles, this makes a convenient way of automatically indexing
each entry name at its location in the glossary without
fiddling around with the value of the \gloskey{name} key.

The internal macro used by the \sty{glossaries} package to
write the information to the external glossary file is
modified to check for the \catattr{dualindex} attribute.

In both cases, the indexing is done through
\begin{definition}[\DescribeMacro\glsxtrdoautoindexname]
\cs{glsxtrdoautoindexname}\marg{label}\marg{attribute-label}
\end{definition}
This uses the standard \ics{index} command with the sort value 
taken from the entry's \gloskey{sort} key and the actual value 
set to \cs{glsentryname}\marg{label}.  If the value of the 
attribute given by \meta{attribute-label} is \qt{true}, no encap 
will be added, otherwise the encap will be the
attribute value. For example:
\begin{verbatim}
\glssetcategoryattribute{general}{indexname}{textbf}
\end{verbatim}
will set the encap to \texttt{textbf} which will display the
relevant page number in bold whereas
\begin{verbatim}
\glssetcategoryattribute{general}{dualindex}{true}
\end{verbatim}
won't apply any formatting to the page number in the index.

\begin{important}
The location used in the index will always be the page number
not the counter used in the glossary. (Unless some other loaded
package has modified the definition of \cs{index} to use
some thing else.)
\end{important}

By default the \gloskey[glslink]{format} key won't be used with 
the \catattr{dualindex} attribute. You can allow the 
\gloskey[glslink]{format} key to override the attribute value
by using the preamble-only command:
\begin{definition}[\DescribeMacro\GlsXtrEnableIndexFormatOverride]
\cs{GlsXtrEnableIndexFormatOverride}
\end{definition}
If you use this command and \sty{hyperref} has been loaded, 
then the \env{theindex} environment will be modified to redefine 
\ics{glshypernumber} to allow formats that use that command.

\begin{important}
The \catattr{dualindex} attribute will still be used on 
subsequent use even if the \catattr{indexonlyfirst} attribute
(or \pkgopt{indexonlyfirst} package option) is set. However,
the \catattr{dualindex} attribute will honour the 
\gloskey[glslink]{noindex} key.
\end{important}

The \cs{glsxtrdoautoindexname} command will attempt to escape any of
\ics{makeindex}'s special characters, but there may be special cases
where it fails, so take care.  This assumes the default \gls{makeindex} actual,
level, quote and encap values (unless any of the commands
\ics{actualchar}, \ics{levelchar}, \ics{quotechar} or
\ics{encapchar} have been defined before \styfmt{glossaries-extra}
is loaded).

If this isn't the case, you can use the following preamble-only
commands to set the correct characters.
\begin{important}
Be very careful of possible shifting category codes!
\end{important}

\begin{definition}[\DescribeMacro\GlsXtrSetActualChar]
\cs{GlsXtrSetActualChar}\marg{char}
\end{definition}
Set the actual character to \meta{char}.

\begin{definition}[\DescribeMacro\GlsXtrSetLevelChar]
\cs{GlsXtrSetLevelChar}\marg{char}
\end{definition}
Set the level character to \meta{char}.

\begin{definition}[\DescribeMacro\GlsXtrSetEscChar]
\cs{GlsXtrSetEscChar}\marg{char}
\end{definition}
Set the escape (quote) character to \meta{char}.

\begin{definition}[\DescribeMacro\GlsXtrSetEncapChar]
\cs{GlsXtrSetEncapChar}\marg{char}
\end{definition}
Set the encap character to \meta{char}.

\chapter{On-the-Fly Document Definitions}
\label{sec:onthefly}

\begin{important}
The commands described here may superficially look like
\meta{word}\cs{index}\marg{word}, but they behave rather 
differently. If you want to use \cs{index} then just use
\cs{index}.
\end{important}

The \sty{glossaries} package advises against defining entries
in the \env{document} environment. As mentioned in
\sectionref{sec:pkgopts} above, this ability is disabled by
default with \styfmt{glossaries-extra} but can be enabled using
the \pkgopt{docdefs} package options.

Although this can be problematic, the \styfmt{glossaries-extra}
package provides a way of defining and using entries within
the \env{document} environment without the tricks used with the
\pkgopt{docdefs} option. \emph{There are limitations with this
approach, so take care with it.} This function is disabled by
default, but can be enabled using the preamble-only command:
\begin{definition}[\DescribeMacro\GlsXtrEnableOnTheFly]
\cs{GlsXtrEnableOnTheFly}
\end{definition}
When used, this defines the commands described below.

\begin{important}
The commands \cs{glsxtr}, \cs{glsxtrpl}, \cs{Glsxtr}
and \cs{Glsxtrpl} can't be used after the glossaries have been
displayed (through \ics{printglossary} etc). It's best not to mix
these commands with the standard glossary commands, such
as \cs{gls} or there may be unexpected results.
\end{important}

\begin{definition}[\DescribeMacro\glsxtr]
\cs{glsxtr}\oarg{gls-options}\oarg{dfn-options}\marg{label}
\end{definition}
If an entry with the label \meta{label} has already been defined,
this just does \cs{gls}\oarg{gls-options}\marg{label}. If
\meta{label} hasn't been defined, this will define the entry
using:
\begin{alltt}
\cs{newglossaryentry}\marg{label}\{name=\marg{label},
 category=\cs{glsxtrcat},
 description=\{\cs{nopostdesc}\},
 \meta{dfn-options}\}
\end{alltt}

\begin{important}
The \meta{label} must contain any non-expandable commands, such as
formatting commands or problematic characters.
If the term requires any of these, they must be omitted from the
\meta{label} and placed in the \gloskey{name} key must be provided
in the optional argument \meta{dfn-options}.
\end{important}

The second optional argument \meta{dfn-options} should be empty
if the entry has already been defined, since it's too late for
them. If it's not empty, a~warning will be generated with
\begin{definition}[\DescribeMacro\GlsXtrWarning]
\cs{GlsXtrWarning}\marg{dfn-options}\marg{label}
\end{definition}

For example, this warning will be generated on the second instance
of \cs{glsxtr} below:
\begin{verbatim}
\glsxtr[][plural=geese]{goose}
% ... later
\glsxtr[][plural=geese]{goose}
\end{verbatim}

If you are considering doing something like:
\begin{verbatim}
\newcommand*{\goose}{\glsxtr[][plural=geese]{goose}}
\renewcommand*{\GlsXtrWarning}[2]{}
% ... later
\goose\ some more text here
\end{verbatim}
then don't bother. It's simpler and less problematic to just
define the entries in the preamble with \ics{newglossaryentry}
and then use \cs{gls} in the document.

There are plural and case-changing alternatives to \cs{glsxtr}:
\begin{definition}[\DescribeMacro\glsxtrpl]
\cs{glsxtrpl}\oarg{gls-options}\oarg{dfn-options}\marg{label}
\end{definition}
This is like \cs{glsxtr} but uses \cs{glspl} instead of \cs{gls}.

\begin{definition}[\DescribeMacro\Glsxtr]
\cs{Glsxtr}\oarg{gls-options}\oarg{dfn-options}\marg{label}
\end{definition}
This is like \cs{glsxtr} but uses \cs{Gls} instead of \cs{gls}.

\begin{definition}[\DescribeMacro\Glsxtrpl]
\cs{Glsxtrpl}\oarg{gls-options}\oarg{dfn-options}\marg{label}
\end{definition}
This is like \cs{glsxtr} but uses \cs{Glspl} instead of \cs{gls}.

If you use UTF-8 and don't want the inconvenient of needing
to use an ASCII-only label, then it's better to use
\XeLaTeX\ or \LuaLaTeX\ instead of \LaTeX\ (or \pdfLaTeX).
If you really desperately want to use UTF-8 entry labels without
switching to \XeLaTeX\ or \LuaLaTeX\ then there is a starred
version of \cs{GlsXtrEnableOnTheFly} that allows you to
use UTF-8 characters in \meta{label}, but it's experimental and 
may not work in some cases.

\begin{important}
If you use the starred version of \cs{GlsXtrEnableOnTheFly}
don't use any commands in the \meta{label}, even if they expand
to just text.
\end{important}

\chapter{Supplemental Packages}
\label{sec:supplemental}

The \sty{glossaries} bundle provides additional support packages
\sty{glossaries-prefix} (for prefixing) and \sty{glossaries-accsupp}
(for accessibility support). These packages aren't automatically
loaded.

\section{Prefixes or Determiners}
\label{sec:prefix}

If prefixing is required, you can simply load
\sty{glossaries-prefix} after \styfmt{glossaries-extra}. For example:
\begin{verbatim}
\documentclass{article}

\usepackage{glossaries-extra}
\usepackage{glossaries-prefix}

\makeglossaries

\newabbreviation
 [prefix={an\space},
 prefixfirst={a~}]
 {svm}{SVM}{support vector machine}

\begin{document}

First use: \pgls{svm}.
Next use: \pgls{svm}.

\printglossaries

\end{document}
\end{verbatim}

\section{Accessibility Support}
\label{sec:accsupp}

The \sty{glossaries-accsupp} needs to be loaded before
\styfmt{glossaries-extra} or through the \pkgopt{accsupp} package
option:
\begin{verbatim}
\usepackage[accsupp]{glossaries-extra}
\end{verbatim}
If you don't load \sty{glossaries-accsupp} or you load
\sty{glossaries-accsupp} after \styfmt{glossaries-extra}
the new \cs{glsaccess}\meta{xxx} commands described below will
simply be equivalent to the corresponding \cs{glsentry}\meta{xxx}
commands.

The following \cs{glsaccess}\meta{xxx} commands add accessibility information wrapped around
the corresponding \cs{glsentry}\meta{xxx} commands. There is
no check for existence of the entry nor do any of these commands
add formatting, hyperlinks or indexing information.

\begin{definition}[\DescribeMacro\glsaccessname]
\cs{glsaccessname}\marg{label}
\end{definition}
This displays the value of the \gloskey{name} field for the entry
identified by \meta{label}.

If the \sty{glossaries-accsupp} package isn't loaded, this is 
simply defined as:
\begin{verbatim}
\newcommand*{\glsaccessname}[1]{\glsentryname{#1}}
\end{verbatim}
otherwise it's defined as:
\begin{verbatim}
\newcommand*{\glsaccessname}[1]{%
  \glsnameaccessdisplay
  {%
    \glsentryname{#1}%
  }%
  {#1}%
}
\end{verbatim}
(\ics{glsnameaccessdisplay} is defined by the
\sty{glossaries-accsupp} package.) The first letter upper case
version is:
\begin{definition}[\DescribeMacro\Glsaccessname]
\cs{Glsaccessname}\marg{label}
\end{definition}
Without the \sty{glossaries-accsupp} package this is just defined 
as:
\begin{verbatim}
\newcommand*{\Glsaccessname}[1]{\Glsentryname{#1}}
\end{verbatim}
With the \sty{glossaries-accsupp} package this is defined as:
\begin{verbatim}
\newcommand*{\Glsaccessname}[1]{%
  \glsnameaccessdisplay
  {%
    \Glsentryname{#1}%
  }%
  {#1}%
}
\end{verbatim}

The following commands are all defined in an analogous manner.
\begin{definition}[\DescribeMacro\glsaccesstext]
\cs{glsaccesstext}\marg{label}
\end{definition}
This displays the value of the \gloskey{text} field.

\begin{definition}[\DescribeMacro\Glsaccesstext]
\cs{Glsaccesstext}\marg{label}
\end{definition}
This displays the value of the \gloskey{text} field with the first
letter converted to upper case.

\begin{definition}[\DescribeMacro\glsaccessplural]
\cs{glsaccessplural}\marg{label}
\end{definition}
This displays the value of the \gloskey{plural} field.

\begin{definition}[\DescribeMacro\Glsaccessplural]
\cs{Glsaccessplural}\marg{label}
\end{definition}
This displays the value of the \gloskey{plural} field
with the first letter converted to upper case.

\begin{definition}[\DescribeMacro\glsaccessfirst]
\cs{glsaccessfirst}\marg{label}
\end{definition}
This displays the value of the \gloskey{first} field.

\begin{definition}[\DescribeMacro\Glsaccessfirst]
\cs{Glsaccessfirst}\marg{label}
\end{definition}
This displays the value of the \gloskey{first} field
with the first letter converted to upper case.

\begin{definition}[\DescribeMacro\glsaccessfirstplural]
\cs{glsaccessfirstplural}\marg{label}
\end{definition}
This displays the value of the \gloskey{firstplural} field.

\begin{definition}[\DescribeMacro\Glsaccessfirstplural]
\cs{Glsaccessfirstplural}\marg{label}
\end{definition}
This displays the value of the \gloskey{firstplural} field
with the first letter converted to upper case.

\begin{definition}[\DescribeMacro\glsaccesssymbol]
\cs{glsaccesssymbol}\marg{label}
\end{definition}
This displays the value of the \gloskey{symbol} field.

\begin{definition}[\DescribeMacro\Glsaccesssymbol]
\cs{Glsaccesssymbol}\marg{label}
\end{definition}
This displays the value of the \gloskey{symbol} field
with the first letter converted to upper case.

\begin{definition}[\DescribeMacro\glsaccesssymbolplural]
\cs{glsaccesssymbolplural}\marg{label}
\end{definition}
This displays the value of the \gloskey{symbolplural} field.

\begin{definition}[\DescribeMacro\Glsaccesssymbolplural]
\cs{Glsaccesssymbolplural}\marg{label}
\end{definition}
This displays the value of the \gloskey{symbolplural} field
with the first letter converted to upper case.

\begin{definition}[\DescribeMacro\glsaccessdesc]
\cs{glsaccessdesc}\marg{label}
\end{definition}
This displays the value of the \gloskey{desc} field.

\begin{definition}[\DescribeMacro\Glsaccessdesc]
\cs{Glsaccessdesc}\marg{label}
\end{definition}
This displays the value of the \gloskey{desc} field
with the first letter converted to upper case.

\begin{definition}[\DescribeMacro\glsaccessdescplural]
\cs{glsaccessdescplural}\marg{label}
\end{definition}
This displays the value of the \gloskey{descplural} field.

\begin{definition}[\DescribeMacro\Glsaccessdescplural]
\cs{Glsaccessdescplural}\marg{label}
\end{definition}
This displays the value of the \gloskey{descplural} field
with the first letter converted to upper case.

\begin{definition}[\DescribeMacro\glsaccessshort]
\cs{glsaccessshort}\marg{label}
\end{definition}
This displays the value of the \gloskey{short} field.

\begin{definition}[\DescribeMacro\Glsaccessshort]
\cs{Glsaccessshort}\marg{label}
\end{definition}
This displays the value of the \gloskey{short} field with the first
letter converted to upper case.

\begin{definition}[\DescribeMacro\glsaccessshortpl]
\cs{glsaccessshortpl}\marg{label}
\end{definition}
This displays the value of the \gloskey{shortplural} field.

\begin{definition}[\DescribeMacro\Glsaccessshortpl]
\cs{Glsaccessshortpl}\marg{label}
\end{definition}
This displays the value of the \gloskey{shortplural} field with the first
letter converted to upper case.

\begin{definition}[\DescribeMacro\glsaccesslong]
\cs{glsaccesslong}\marg{label}
\end{definition}
This displays the value of the \gloskey{long} field.

\begin{definition}[\DescribeMacro\Glsaccesslong]
\cs{Glsaccesslong}\marg{label}
\end{definition}
This displays the value of the \gloskey{long} field with the first
letter converted to upper case.

\begin{definition}[\DescribeMacro\glsaccesslongpl]
\cs{glsaccesslongpl}\marg{label}
\end{definition}
This displays the value of the \gloskey{longplural} field.

\begin{definition}[\DescribeMacro\Glsaccesslongpl]
\cs{Glsaccesslongpl}\marg{label}
\end{definition}
This displays the value of the \gloskey{longplural} field with the first
letter converted to upper case.

\chapter{Sample Files}
\label{sec:samples}

The following sample files are provided with this package:
\begin{description}
\item[sample.tex] Simple sample file that uses one of the dummy
files provided by the \sty{glossaries} package for testing.

\item[sample-mixture.tex] General entries, acronyms and initialisms
all treated differently.

\item[sample-abbrv.tex] General abbreviations.

\item[sample-acronym.tex] Acronyms aren't initialisms and don't
expand on \gls{firstuse}.

\item[sample-acronym-desc.tex] Acronyms that have a separate long
form and description.

\item[sample-crossref.tex] Unused entries that have been
cross-referenced automatically are added at the end of the document.

\item[sample-indexhook.tex] Use the index hook to track
which entries have been indexed (and therefore find out
which ones haven't been indexed).

\item[sample-footnote.tex] Footnote abbreviation style that moves
the footnote marker outside of the hyperlink generated by \cs{gls} 
and moves it after certain punctuation characters for neatness.

\item[sample-undef.tex] Warn on undefined entries instead of
generating an error.

\item[sample-mixed-abbrv-styles.tex] Different abbreviation styles
for different entries.

\item[sample-initialisms.tex] Automatically insert dots into
initialisms.

\item[sample-postdot.tex] Another initialisms example.

\item[sample-postlink.tex] Automatically inserting text after
the \gls{linktext} produced by commands like \cs{gls} (outside 
of hyperlink, if present).

\item[sample-header.tex] Using entries in section/chapter headings.

\item[sample-autoindex.tex] Using the \catattr{dualindex} and
\catattr{indexname} attributes to automatically add glossary
entries to the index (in addition to the glossary \gls{locationlist}).

\item[sample-autoindex-hyp.tex] As previous but uses \sty{hyperref}.

\item[sample-nested.tex] Using \ics{gls} within the
value of the \gloskey{name} key.

\item[sample-entrycount.tex] Enable entry-use counting (only index
if used more than $n$ times).

\item[sample-unitentrycount.tex] Enable use of per-unit entry-use counting.

\item[sample-onelink.tex] Using the per-unit entry counting
to only have one hyperlink per entry per page.

\item[sample-altmodifier.tex] Set the default options for
commands like \cs{gls} and add an alternative modifier.

\item[sample-onthefly.tex] Using on-the-fly commands. Terms with
accents must have the \gloskey{name} key explicitly set.

\item[sample-onthefly-xetex.tex] Using on-the-fly commands
with \XeLaTeX. Terms with UTF-8 characters don't need to
have the \gloskey{name} key explicitly set. Terms that contain
commands must have the \gloskey{name} key explicitly set
with the commands removed from the label.

\item[sample-onthefly-utf8.tex] Tries to emulate the previous
sample file for use with \LaTeX\ through the starred version
of \ics{GlsXtrEnableOnTheFly}. This is a bit iffy and may not
always work. Terms that contain commands must have the 
\gloskey{name} key explicitly set with the commands removed from 
the label.

\item[sample-accsupp.tex] Integrate \sty{glossaries-accsupp}.

\item[sample-prefix.tex] Integrate \sty{glossaries-prefix}.

\end{description}

\chapter{Multi-Lingual Support}
\label{sec:lang}

There's only one command provided by \styfmt{glossaries-extra} 
that you're likely to want to change in your document and that's
\ics{abbreviationsname} (\sectionref{sec:pkgopts}) if you use
the \pkgopt{abbreviations} package option to automatically
create the glossary labelled \texttt{abbreviations}. If this
command doesn't already exist, it will be defined to
\qt{Abbreviations} if \sty{babel} hasn't been loaded, otherwise
it will be defined as \cs{acronymname} (provided by
\sty{glossaries}).

You can redefine it in the usual way. For example:
\begin{verbatim}
\renewcommand*{\abbreviationsname}{List of Abbreviations}
\end{verbatim}
Or using \sty{babel} or \sty{polyglossia} captions hook:
\begin{verbatim}
\appto\captionsenglish{%
 \renewcommand*{\abbreviationsname}{List of Abbreviations}%
}
\end{verbatim}

Alternatively you can use the \gloskey[printglossary]{title}
key when you print the list of abbreviations. For example:
\begin{verbatim}
\printabbreviations[title={List of Abbreviations}]
\end{verbatim}
or
\begin{verbatim}
\printglossary[type=abbreviations,title={List of Abbreviations}]
\end{verbatim}

The other fixed text commands are the diagnostic messages, which
shouldn't appear in the final draft of your document.

The \styfmt{glossaries-extra} package has the facility to load
language modules if they exist, but won't warn if they don't.

If you want to write your own language module, you just need to
create a file called
\texttt{glossariesxtr-}\meta{lang}\texttt{.ldf}, where \meta{lang}
is the language name (see the \sty{tracklang} package). For example,
\texttt{glossariesxtr-french.ldf}.

The simplest code for this file is:
\begin{verbatim}
\ProvidesGlossariesExtraLang{french}[2015/12/09 v1.0]

\newcommand*{\glossariesxtrcaptionsfrench}{%
 \def\abbreviationsname{Abr\'eviations}%
}
\glossariesxtrcaptionsfrench

\ifcsdef{captions\CurrentTrackedDialect}
{%
  \csappto{captions\CurrentTrackedDialect}%
  {%
    \glossariesxtrcaptionsfrench
  }%
}%
{%
  \ifcsdef{captions\CurrentTrackedLanguage}
  {%
    \csappto{captions\CurrentTrackedLanguage}%
    {%
      \glossariesxtrcaptionsfrench
    }%
  }%
  {%
  }%
  \glossariesxtrcaptionsfrench
}
\end{verbatim}

You can adapt this for other languages by replacing 
all instances of the language identifier \texttt{french} and
the translated text \verb|Abr\'eviations| as appropriate.
This \texttt{.ldf} file then needs to be put somewhere on \TeX's
path so that it can be found by \styfmt{glossaries-extra}.
You might also want to consider uploading it to CTAN so that
it can be useful to others. (Please don't send it to me. I already
have more packages than I am able to maintain.)

If you additionally want to provide translations for the diagnostic
messages used when a glossary is missing, you need to redefine
the following commands:
\begin{definition}[\DescribeMacro\GlsXtrNoGlsWarningHead]
\cs{GlsXtrNoGlsWarningHead}\marg{label}\marg{file}
\end{definition}
This produces the following text in English:
\begin{quote}
\GlsXtrNoGlsWarningHead{\meta{label}}{\meta{file}}
\end{quote}

\begin{definition}[\DescribeMacro\GlsXtrNoGlsWarningEmptyStart]
\cs{GlsXtrNoGlsWarningEmptyStart}
\end{definition}
This produces the following text in English:
\begin{quote}
\GlsXtrNoGlsWarningEmptyStart
\end{quote}

\begin{definition}[\DescribeMacro\GlsXtrNoGlsWarningEmptyMain]
\cs{GlsXtrNoGlsWarningEmptyMain}
\end{definition}
This produces the following text in English:
\begin{quote}
\GlsXtrNoGlsWarningEmptyMain
\end{quote}

\begin{definition}[\DescribeMacro\GlsXtrNoGlsWarningEmptyNotMain]
\cs{GlsXtrNoGlsWarningEmptyNotMain}\marg{label}
\end{definition}
This produces the following text in English:
\begin{quote}
\GlsXtrNoGlsWarningEmptyNotMain{\meta{label}}
\end{quote}

\begin{definition}[\DescribeMacro\GlsXtrNoGlsWarningCheckFile]
\cs{GlsXtrNoGlsWarningCheckFile}\marg{file}
\end{definition}
This produces the following text in English:
\begin{quote}
\GlsXtrNoGlsWarningCheckFile{\meta{file}}
\end{quote}

\begin{definition}[\DescribeMacro\GlsXtrNoGlsWarningMisMatch]
\cs{GlsXtrNoGlsWarningMisMatch}
\end{definition}
This produces the following text in English:
\begin{quote}
\GlsXtrNoGlsWarningMisMatch
\end{quote}

\begin{definition}[\DescribeMacro\GlsXtrNoGlsWarningNoOut]
\cs{GlsXtrNoGlsWarningNoOut}\marg{file}
\end{definition}
This produces the following text in English:
\begin{quote}
\GlsXtrNoGlsWarningNoOut{\meta{file}}
\end{quote}

\begin{definition}[\DescribeMacro\GlsXtrNoGlsWarningTail]
\cs{GlsXtrNoGlsWarningTail}
\end{definition}
This produces the following text in English:
\begin{quote}
\GlsXtrNoGlsWarningTail
\end{quote}

\begin{definition}[\DescribeMacro\GlsXtrNoGlsWarningBuildInfo]
\cs{GlsXtrNoGlsWarningBuildInfo}
\end{definition}
This is advice on how to generate the glossary files.
See the documented code (\texttt{glossaries-extra-code.pdf})
for further details.

\begin{definition}[\DescribeMacro\GlsXtrNoGlsWarningAutoMake]
\cs{GlsXtrNoGlsWarningAutoMake}\marg{label}
\end{definition}
This is the message produced when the \pkgopt{automake} option
is used, but the document needs a rerun or the shell escape
setting doesn't permit the execution of the external application.
This command also generates a warning in the transcript file.
See the documented code for further details.

\printglossaries
\PrintIndex

\end{document}