% \iffalse meta-comment
%
% Copyright 1993 1994 1995 1996 1997 1998 1999
% The LaTeX3 Project and any individual authors listed elsewhere
% in this file.
%
% This file is part of the LaTeX2e system.
% ----------------------------------------
%
% It may be distributed under the terms of the LaTeX Project Public
% License, as described in lppl.txt in the base LaTeX distribution.
% Either version 1.0 or, at your option, any later version.
%
% \fi
% \iffalse
%%% From File: ltlists.dtx
%<*driver>
% \fi
\ProvidesFile{ltlists.dtx}
[1997/02/21 v1.0r LaTeX Kernel (List Environments)]
% \iffalse
\documentclass{ltxdoc}
\GetFileInfo{ltlists.dtx}
\title{\filename}
\date{\filedate}
\author{%
Johannes Braams\and
David Carlisle\and
Alan Jeffrey\and
Leslie Lamport\and
Frank Mittelbach\and
Tobias Oetiker\thanks{Tobi has converted the documentation to
doc.sty standard}\and
Chris Rowley\and
Rainer Sch\"opf}
\begin{document}
\maketitle
\DocInput{\filename}
\end{document}
%</driver>
% \fi
%
% \CheckSum{494}
%
% \changes{v1.0b}{1994/03/28}{Improve documentation}
% \changes{v1.0f}{1994/05/21}{Use new error commands}
% \changes{v1.0f}{1995/05/21}{Moved to doc.sty standard}
%
% \section{List, and related environments}
%
% The generic commands for creating an indented environment --
% |enumerate|, |itemize|, |quote|, etc -- are:
% \begin{quote}
% |\list|\marg{LABEL}\marg{COMMANDS} ... |\endlist|
% \end{quote}
%
% which can be invoked by the user as the list environment. The LABEL
% argument specifies item labeling. COMMANDS contains commands for
% changing the horizontal and vertical spacing parameters.
%
% Each item of the environment is begun by the command
% |\item[|ITEMLABEL|]|
% which produces an item labeled by ITEMLABEL. If the argument is
% missing, then the LABEL argument of the |\list| command is used as the
% item label.
%
% The label is formed by putting |\makelabel|\marg{ITEMLABEL} in an hbox
% whose width is either its natural width or else |\labelwidth|,
% whichever is larger. The |\list| command defines |\makelabel| to have
% the default definition:
% \begin{quote}
% |\makelabel|\marg{ARG} == BEGIN |\hfil| ARG END
% \end{quote}
% which, for a label of width less than |\labelwidth|, puts the label
% flushright, |\labelsep| to the left of the item's text. However,
% |\makelabel| can be |\let| to another command by the |\list|'s
% COMMANDS argument.
%
% A |\usecounter|\marg{foo} command in the second argument causes the
% counter \emph{foo} to be initialized to zero, and stepped by every
% |\item| command without an argument. (|\label| commands within the
% list refer to this counter.)
%
% When you leave a list environment, returning either to an enclosing
% list or normal text mode, LaTeX begins a new paragraph if and only if
% you leave a blank line after the |\end| command. This is accomplished
% by the |\@endparenv| command.
%
% Blank lines are ignored every other reasonable place--i.e.:
% \begin{itemize}
% \item Between the |\begin{list}| and the first |\item|,
% \item Between the |\item| and the text of that item.
% \item Between the end of the last item and the |\end{list}|.
% \end{itemize}
%
% For an environment like quotation, in which items are not labeled,
% the entire environment is a single item. It is defined by
% letting |\quotation| == |\list{}{...}\item\relax|. (Note the
% |\relax|, there in case the first character in the environment is a
% '['.) The spacing parameters provide a great deal of flexability in
% designing the format, including the ability to let the indentation of
% the first paragraph be different from that of the subsequent ones.
%
% The trivlist environment is equivalent to a list environment
% whose second argument sets the following parameter values:
% \begin{description}
% \item[\cs{leftmargin} = 0:] causes no indentation of left margin
% \item[\cs{labelwidth} = 0:] see below for precise effect this has.
% \item[\cs{itemindent} = 0:] with a null label, makes first paragraph
% have no indentation. Succeeding paragraphs have |\parindent|
% indentation. To give first paragraph same indentation, set
% |\itemindent| = |\parindent| before the |\item[]|.
% \end{description}
%
% Every |\item| in a trivlist environment must have an argument---in
% many cases, this will be the null argument (|\item[]|). The trivlist
% environment is mainly used for paragraphing environments, like
% verbatim, in which there is no margin change. It provides the same
% vertical spacing as the list environment, and works reasonably well
% when it occurs immediately after an |\item| command in an enclosing
% list.
%
% \StopEventually{}
%
%
% \changes{v1.0a}{1994/03/07}{Initial version, split from latex.dtx}
% \changes{v1.0a}{1994/03/07}{Long lines wrapped to 72 columns}
%
%
% \subsection{List and Trivlist}
%
%
% The following variables are used inside a list environment:
% \begin{description}
% \item[\cs{@totalleftmargin}] The distance that the prevailing left
% margin is indented from the outermost left margin,
% \item[\cs{linewidth}] The width of the current line. Must be
% initialized to |\hsize|.
% \item[\cs{@listdepth}] A count for holding current list nesting depth.
% \item[\cs{makelabel}] A macro with a single argument, used to
% generate the label from the argument (given or implied)
% of the |\item| command. Initialized to |\@mklab| by the |\list|
% command. This command must produce some stretch---i.e., an
% |\hfil|.
% \item[\cs{@inlabel}] A switch that is false except between the time
% an |\item| is encountered and the time that \TeX{}
% actually enters horizontal mode. Should be tested by commands
% that can be messed up by the list environment's use of |\everypar|.
% \item[\cs{box\@labels}] When |@inlabel = true|, it holds the labels
% to be put out by |\everypar|.
% \item[\texttt{@noparitem}] A switch set by |\list| when
% |@inlabel = true|.
% Handles the case of a |\list| being the first thing in an item.
% \item[\texttt{@noparlist}] A switch set true for a list that begins an
% item. No |\topsep| space is added before or after |\item|'s such a
% list.
% \item[\texttt{@newlist}] Set true by |\list|, set false by the first
% text (by |\everypar|).
% \item[\texttt{@noitemarg}] Set true when executing an |\item| with no
% explicit argument. Used to save space. To save time, make two
% separate |\@item| commands.
% \item[\texttt{@nmbrlist}] Set true by |\usecounter| command, causes
% list to be numbered.
% \item[\cs{@listctr}] |\def|'ed by |\usecounter| to name of counter.
% \item[\cs{@noskipsec}] A switch set true by a sectioning command when
% it is creating an in-text heading with |\everypar|.
% \end{description}
%
% Throughout a list environment, |\hsize| is the width of the current
% line, measured from the outermost left margin to the outermost right
% margin. Environments like tabbing should use |\linewidth| instead of
% |\hsize|.
%
% Here are the parameters of a list that can be set by commands in
% the |\list|'s COMMANDS argument. These parameters are all TeX
% skips or dimensions (defined by |\newskip| or |\newdimen|), so the
% usual \TeX\ or \LaTeX\ commands can be used to set them. The
% commands will be executed in vmode if and only if the |\list| was
% preceded by a |\par| (or something like an |\end{list}|), so the
% spacing parameters can be set according to whether the list is
% inside a paragraph or is its own paragraph.
%
%
% \subsection{Vertical Spacing (skips)}
% \begin{description}
% \item[\cs{topsep}:] Space between first item and preceding paragraph.
% \item[\cs{partopsep}:] Extra space added to \cs{topsep} when
% environment starts a new paragraph (is called in vmode).
% \item[\cs{itemsep}:] Space between successive items.
% \item[\cs{parsep}:] Space between paragraphs within an item -- the
% \cs{parskip} for this environment.
% \end{description}
%
% \subsection{Penalties}
% \begin{description}
%
% \item[\cs{@beginparpenalty}:] put at the beginning of a list
% \item[\cs{@endparpenalty}:] put at end of list
% \item[\cs{@itempenalty}:] put between items.
% \end{description}
%
% \subsection{Horizontal Spacing (dimens)}
% \begin{description}
% \item[\cs{leftmargin}:] space between left margin of enclosing
% environment (or of page if top level list) and left margin of
% this list. Must be nonnegative.
% \item[\cs{rightmargin}:] analogous.
% \item[\cs{listparindent}:] extra indentation at beginning of every
% paragraph of a list except the one started by the \cs{item}
% command. May be negative! Usually, labeled
% lists have \cs{listparindent} equal to zero.
% \item[\cs{itemindent}:] extra indentation added right BEFORE an item
% label.
% \item[\cs{labelwidth}:] nominal width of box that contains the label.
% If the natural width of the
% label $< =$ \cs{labelwidth},
% then the label is flushed right inside a box
% of width \cs{labelwidth} (with an \cs{hfil}).
% Otherwise,
% a box of the natural width is employed, which
% causes an indentation of the text on that line.
% \item[\cs{labelsep}:] space between end of label box and text of
% first item.
% \end{description}
% \subsection{Default Values}
% Defaults for the list environment are set as follows.
% First, \cs{rightmargin}, \cs{listparindent} and \cs{itemindent}
% are set
% to 0pt. Then, one of the commands
% \cs{@listi}, \cs{@listii}, ... , \cs{@listvi}
% is called, depending upon the current level of the list.
% The \cs{@list} \ldots commands should be defined by the document
% style. A convention that the document style should follow is
% to set \cs{leftmargin} to
% \cs{leftmargini},\ldots, \cs{leftmarginvi} for
% the appropriate level. Items that aren't changed may be left
% alone, but everything that could possibly be changed must be
% reset.
% \begin{oldcomments}
% \list{LABEL}{COMMANDS} ==
% BEGIN
% if \@listdepth > 5
% then LaTeX error: 'Too deeply nested'
% else \@listdepth :=G \@listdepth + 1
% fi
% \rightmargin := 0pt
% \listparindent := 0pt
% \itemindent := 0pt
% \eval(@list \romannumeral\the\@listdepth) %% Set default values:
% \@itemlabel :=L LABEL
% \makelabel == \@mklab
% @nmbrlist :=L false
% COMMANDS
%
% \@trivlist % commands common to \list and \trivlist
%
% \parskip :=L \parsep
% \parindent :=L \listparindent
% \linewidth :=L \linewidth - \rightmargin -\leftmargin
% \@totalleftmargin :=L \@totalleftmargin + \leftmargin
% \parshape 1 \@totalleftmargin \linewidth
% \ignorespaces % gobble space up to \item
% END
%
% \endlist == BEGIN \@listdepth :=G \@listdepth -1
% \endtrivlist
% END
%
% \@trivlist ==
% BEGIN
% if @newlist = T then \@noitemerr fi
% %% This command removed for some forgotten reason.
% \@topsepadd :=L \topsep
% if @noskipsec then leave vertical mode fi %% Added 11 Jun 85
% if vertical mode
% then \@topsepadd :=L \@topsepadd + \partopsep
% else \unskip \par % remove glue from end of last line
% fi
% if @inlabel = true
% then @noparitem :=L true
% @noparlist :=L true
% else @noparlist :=L false
% \@topsep :=L \@topsepadd
% fi
% \@topsep :=L \@topsep + \parskip %% Change 4 Sep 85
% \leftskip :=L 0pt % Restore paragraphing parameters
% \rightskip :=L \@rightskip
% \parfillskip :=L 0pt + 1fil
%
% NOTE: \@setpar called on every \list in case \par has been
% temporarily munged before the \list command.
% \@setpar{if @newlist = false then {\@@par} fi}
% \@newlist :=G T
% \@outerparskip :=L \parskip
% END
%
% \trivlist ==
% BEGIN
% \parsep := \parskip
% @nmbrlist := F
% \@trivlist
% \labelwidth := 0
% \leftmargin := 0
% \itemindent := \parindent
% \@itemlabel :=L "empty" %% added 93/12/13
% \makelabel{LABEL} == LABEL
% END
%
% \endtrivlist ==
% BEGIN
% if @inlabel = T then \indent fi
% if horizontal mode then \unskip \par fi
% if @noparlist = true
% else if \lastskip > 0
% then \@tempskipa := \lastskip
% \vskip - \lastskip
% \vskip \@tempskipa -\@outerparskip + \parskip
% fi
% \@endparenv
% fi
% END
%
% \@endparenv ==
% BEGIN
% \addpenalty{@endparpenalty}
% \addvspace{\@topsepadd}
% \endgroup %% ends the \begin command's \begingroup
% \par == BEGIN
% \@restorepar
% \everypar{}
% \par
% END
% \everypar == BEGIN remove \lastbox \everypar{} END
% \begingroup %% to match the \end commands \endgroup
% END
%
% \item == BEGIN if math mode then WARNING fi
% if next char = [
% then \@item
% else @noitemarg := true
% \@item[@itemlabel]
% END
%
% \@item[LAB] ==
% BEGIN
% if @noparitem = true
% then @noparitem := false
% % NOTE: then clause hardly every taken,
% % so made a macro \@donoparitem
% \box\@labels :=G \hbox{\hskip -\leftmargin
% \box\@labels
% \hskip \leftmargin }
% if @minipage = false then
% \@tempskipa := \lastskip
% \vskip -\lastskip
% \vskip \@tempskipa + \@outerparskip - \parskip
% fi
% else if @inlabel = true
% then \indent \par % previous item empty.
% fi
% if hmode then 2 \unskip's
% % To remove any space at end of prev.
% % paragraph that could cause a blank line.
% \par
% fi
% if @newlist = T
% then if @nobreak = T % Kludge if list follows \section
% then \addvspace{\@outerparskip - \parskip}
% else \addpenalty{\@beginparpenalty}
% \addvspace{\@topsep}
% \addvspace{-\parskip} %% added 4 Sep 85
% fi
% else \addpenalty{\@itempenalty}
% \addvspace{\itemsep}
% fi
% @inlabel :=G true
% fi
%
% \everypar{ @minipage :=G F
% @newlist :=G F
% if @inlabel = true
% then @inlabel :=G false
% \hskip -\parindent
% \box\@labels
% \penalty 0
% %% 3 Oct 85 -- allow line break here
% \box\@labels :=G null
% fi
% \everypar{} }
% @nobreak :=G false
% if @noitemarg = true
% then @noitemarg := false
% if @nmbrlist
% then \refstepcounter{\@listctr}
% fi fi
% \@tempboxa :=L \hbox{\makelabel{LAB}}
% \box\@labels :=G \@labels \hskip \itemindent
% \hskip - (\labelwidth + \labelsep)
% if \wd \@tempboxa > \labelwidth
% then \box\@tempboxa
% else \hbox to \labelwidth {\unhbox\@tempboxa}
% fi
% \hskip\labelsep
% \ignorespaces %gobble space up to text
% END
%
% \makelabel{LABEL} == ERROR %% default to catch lonely \item
%
%
% \usecounter{CTR} == BEGIN @nmbrlist :=L true
% \@listctr == CTR
% \setcounter{CTR}{0}
% END
%
% DEFINE \dimen's and \count
% \end{oldcomments}
% \begin{macro}{\topskip}
% \begin{macro}{\partopsep}
% \begin{macro}{\itemsep}
% \begin{macro}{\parsep}
% \begin{macro}{\@topsep}
% \begin{macro}{\@topsepadd}
% \begin{macro}{\outerparskip}
% \begin{macrocode}
%<*2ekernel>
\newskip\topsep
\newskip\partopsep
\newskip\itemsep
\newskip\parsep
\newskip\@topsep
\newskip\@topsepadd
\newskip\@outerparskip
% \end{macrocode}
% \end{macro}\end{macro}\end{macro}\end{macro}\end{macro}\end{macro}
% \end{macro}
% \begin{macro}{\leftmargin}\begin{macro}{\rightmargin}
% \begin{macro}{\listparindent}\begin{macro}{\itemindent}
% \begin{macro}{\labelwidth}\begin{macro}{\labelsep}
% \begin{macro}{\@totalleftmargin}
% \begin{macrocode}
\newdimen\leftmargin
\newdimen\rightmargin
\newdimen\listparindent
\newdimen\itemindent
\newdimen\labelwidth
\newdimen\labelsep
\newdimen\linewidth
\newdimen\@totalleftmargin \@totalleftmargin=\z@
% \end{macrocode}
% \end{macro}\end{macro}\end{macro}\end{macro}\end{macro}
% \end{macro}\end{macro}
%
% \begin{macro}{\leftmargini}
% \begin{macro}{\leftmarginii}
% \begin{macro}{\leftmarginiii}
% \begin{macro}{\leftmarginiv}
% \begin{macro}{\leftmarginv}
% \begin{macro}{\leftmarginvi}
% \begin{macrocode}
\newdimen\leftmargini
\newdimen\leftmarginii
\newdimen\leftmarginiii
\newdimen\leftmarginiv
\newdimen\leftmarginv
\newdimen\leftmarginvi
% \end{macrocode}
% \end{macro}\end{macro}\end{macro}
% \end{macro}\end{macro}\end{macro}
%
% \begin{macro}{\@listdepth}\begin{macro}{\@itempenalty}
% \begin{macro}{\@beginparpenalty}\begin{macro}{\@endparpenalty}
% \begin{macrocode}
\newcount\@listdepth \@listdepth=0
\newcount\@itempenalty
\newcount\@beginparpenalty
\newcount\@endparpenalty
% \end{macrocode}
% \end{macro}\end{macro}\end{macro}\end{macro}
%
% \begin{macro}{\@labels}
% \begin{macrocode}
\newbox\@labels
% \end{macrocode}
% \end{macro}
%
% \begin{macro}{\if@inlabel}
% \begin{macro}{\@inlabelfalse}
% \begin{macro}{\@inlabeltrue}
% \begin{macrocode}
\newif\if@inlabel \@inlabelfalse
% \end{macrocode}
% \end{macro}\end{macro}\end{macro}
%
% \begin{macro}{\if@newlist}
% \begin{macro}{\@newlistfalse}
% \begin{macro}{\@newlisttrue}
% \begin{macrocode}
\newif\if@newlist \@newlistfalse
% \end{macrocode}
% \end{macro}\end{macro}\end{macro}
%
% \begin{macro}{\if@noparitem}
% \begin{macro}{\@noparitemfalse}
% \begin{macro}{\@noparitemtrue}
% \begin{macrocode}
\newif\if@noparitem \@noparitemfalse
% \end{macrocode}
% \end{macro}\end{macro}\end{macro}
%
% \begin{macro}{\if@noparlist}
% \begin{macro}{\@noparlistfalse}
% \begin{macro}{\@noparlisttrue}
% \begin{macrocode}
\newif\if@noparlist \@noparlistfalse
% \end{macrocode}
% \end{macro}\end{macro}\end{macro}
%
% \begin{macro}{\if@noitemarg}
% \begin{macro}{\@noitemargfalse}
% \begin{macro}{\@noitemargtrue}
% \begin{macrocode}
\newif\if@noitemarg \@noitemargfalse
% \end{macrocode}
% \end{macro}\end{macro}\end{macro}
%
% \begin{macro}{\if@newlist}
% \begin{macro}{\@newlistfalse}
% \begin{macro}{\@newlisttrue}
% \begin{macrocode}
\newif\if@nmbrlist \@nmbrlistfalse
% \end{macrocode}
% \end{macro}\end{macro}\end{macro}
%
% \begin{macro}{\list}
% \begin{macrocode}
\def\list#1#2{%
\ifnum \@listdepth >5\relax
\@toodeep
\else
\global\advance\@listdepth\@ne
\fi
\rightmargin\z@
\listparindent\z@
\itemindent\z@
\csname @list\romannumeral\the\@listdepth\endcsname
\def\@itemlabel{#1}%
\let\makelabel\@mklab
\@nmbrlistfalse
#2\relax
\@trivlist
\parskip\parsep
\parindent\listparindent
\advance\linewidth -\rightmargin
\advance\linewidth -\leftmargin
\advance\@totalleftmargin \leftmargin
\parshape \@ne \@totalleftmargin \linewidth
\ignorespaces}
% \end{macrocode}
% \end{macro}
%
% \begin{macro}{\par@deathcycles}
% \begin{macrocode}
\newcount\par@deathcycles
% \end{macrocode}
% \end{macro}
%
% \begin{macro}{\@trivlist}
% \changes{v1.0e}{1994/12/02}{RmS: Added check for looping}
% \changes{v1.0p}{1996/10/31}{Added check for missing item in outer
% list}
% \changes{v1.0q}{1996/11/04}{Moved check for missing item: only checked
% when not inlabel flag is false}
% Because |\par| is sometimes made a no-op it is possible for a missing
% |\item| to produce a loop that does not fill memory and so never gets
% trapped by \TeX. We thus need to trap this here by seting |\par| to
% count the number of times a paragraph ii is called with no progress
% being made started.
% \begin{macrocode}
\def\@trivlist{%
\if@noskipsec \leavevmode \fi
\@topsepadd \topsep
\ifvmode
\advance\@topsepadd \partopsep
\else
\unskip \par
\fi
\if@inlabel
\@noparitemtrue
\@noparlisttrue
\else
\if@newlist \@noitemerr \fi
\@noparlistfalse
\@topsep \@topsepadd
\fi
\advance\@topsep \parskip
\leftskip \z@skip
\rightskip \@rightskip
\parfillskip \@flushglue
\par@deathcycles \z@
\@setpar{\if@newlist
\advance\par@deathcycles \@ne
\ifnum \par@deathcycles >\@m
\@noitemerr
{\@@par}%
\fi
\else
{\@@par}%
\fi}%
\global \@newlisttrue
\@outerparskip \parskip}
% \end{macrocode}
% \end{macro}
%
% \changes{0.0}{1992/03/18}{RmS: added \cs{@nmbrlistfalse}}
% \begin{macro}{\trivlist}
% \begin{macrocode}
\def\trivlist{%
\parsep\parskip
\@nmbrlistfalse
\@trivlist
\labelwidth\z@
\leftmargin\z@
\itemindent\z@
% \end{macrocode}
%
% We initialise |\@itemlabel| so that a \texttt{trivlist} with
% an |\item| not having an optional argument doesn't produce an
% error message.
% \changes{latex2e}{1993/12/13}{Initialised \cs{@itemlabel}}
% \begin{macrocode}
\let\@itemlabel\@empty
\def\makelabel##1{##1}}
% \end{macrocode}
% \end{macro}
%
% \begin{macro}{\endlist}
% \begin{macrocode}
\def\endlist{%
\global\advance\@listdepth\m@ne
\endtrivlist}
% \end{macrocode}
% \end{macro}
%
% The definition of \cs{trivlist} used to be in ltspace.dtx
% so that other commands could be `let to it'.
% They now use \cs{def}.
% \begin{macro}{\endtrivlist}
% \changes{v1.2b ltspace}{1994/11/12}{Changed order of tests to make
% \cs{@noitemerror} correct: end of an era.}
% \changes{v1.0i}{1995/05/25}{Macros moved from ltspace.dtx}
% \changes{v1.0n}{1996/10/25}{Change \cs{indent} to \cs{leavevmode}}
% \changes{v1.0n}{1996/10/25}{Reset flags explicitly}
% \changes{v1.0o}{1996/10/26}{Correct typo}
% \begin{macrocode}
\def\endtrivlist{%
\if@inlabel
\leavevmode
\global \@inlabelfalse
\fi
\if@newlist
\@noitemerr
\global \@newlistfalse
\fi
\ifhmode\unskip \par\fi
\if@noparlist \else
\ifdim\lastskip >\z@
\@tempskipa\lastskip \vskip -\lastskip
\advance\@tempskipa\parskip \advance\@tempskipa -\@outerparskip
\vskip\@tempskipa
\fi
\@endparenv
\fi
}
% \end{macrocode}
% \end{macro}
%
%
%
% \begin{macro}{\@endparenv}
% \begin{macro}{\@doendpe}
% To suppress the paragraph indentation in text immediately following
% a paragraph-making environment, \cs{everypar} is changed to remove the
% space, and \cs{par} is redefined to restore \cs{everypar}. Instead of
% redefining \cs{par} and \cs{everpar}, \cs{@endparenv} was changed to
% set the @endpe switch, letting \cs{end} redefine \cs{par} and
% \cs{everypar}.
%
% This allows paragraph-making environments to work right when called
% by other environments. (Changed 27 Oct 86)
% \begin{macrocode}
\def\@endparenv{%
\addpenalty\@endparpenalty\addvspace\@topsepadd\@endpetrue}
% \end{macrocode}
%
% \begin{macrocode}
\def\@doendpe{\@endpetrue
\def\par{\@restorepar\everypar{}\par\@endpefalse}\everypar
% \end{macrocode}
%
% Use |\setbox0=\lastbox| instead of |\hskip -\parindent|
% so that a \cs{noindent} becomes a no-op when used before
% a line immediately following a list environment(23 Oct 86).
% \changes{v1.0k}{1995/11/07}{Enclosed \cs{setbox0} assignment by a
% group so that it leaves the contents of box $0$ intact.}
% \begin{macrocode}
{{\setbox\z@\lastbox}\everypar{}\@endpefalse}}
% \end{macrocode}
% \end{macro}
% \end{macro}
%
%
% \begin{macro}{\if@endpe}
% \begin{macro}{\@endpefalse}
% \begin{macro}{\@endpeltrue}
% \begin{macrocode}
\newif\if@endpe
\@endpefalse
% \end{macrocode}
% \end{macro}\end{macro}\end{macro}
%
%
% \begin{macro}{\@mklab}
% \begin{macrocode}
\def\@mklab#1{\hfil #1}
% \end{macrocode}
% \end{macro}
%
% \changes{LaTeX2.09}{1992/09/18}
% {(RmS) Added warning if \cs{item} is used in math mode}
% \changes{v1.0c}{1994/04/28}
% {Replaced \cs{@ltxnomath} by \cs{@inmatherr}}
% \changes{v1.0d}{1994/05/03}
% {Removed superfluous braces}
% \begin{macro}{\item}
% \begin{macrocode}
\def\item{%
\@inmatherr\item
\@ifnextchar [\@item{\@noitemargtrue \@item[\@itemlabel]}}
% \end{macrocode}
% \end{macro}
% \begin{macro}{\@donoparitem}
% \begin{macrocode}
\def\@donoparitem{%
\@noparitemfalse
\global\setbox\@labels\hbox{\hskip -\leftmargin
\unhbox\@labels
\hskip \leftmargin}%
\if@minipage\else
\@tempskipa\lastskip
\vskip -\lastskip
\advance\@tempskipa\@outerparskip
\advance\@tempskipa -\parskip
\vskip\@tempskipa
\fi}
% \end{macrocode}
% \end{macro}
%
% \begin{macro}{\@item}
% \changes{v1.0l}{1996/07/26}{Remove unecessary \cs{global} before
% \cs{@minipage...}}
% \begin{macrocode}
\def\@item[#1]{%
\if@noparitem
\@donoparitem
\else
\if@inlabel
\indent \par
\fi
\ifhmode
\unskip\unskip \par
\fi
\if@newlist
\if@nobreak
\@nbitem
\else
\addpenalty\@beginparpenalty
\addvspace\@topsep
\addvspace{-\parskip}%
\fi
\else
\addpenalty\@itempenalty
\addvspace\itemsep
\fi
\global\@inlabeltrue
\fi
\everypar{%
\@minipagefalse
\global\@newlistfalse
% \end{macrocode}
% This |\if@inlabel| check is needed in case an item starts of
% inside a group so that |\everypar| does not become empty
% outside that group.
% \@nobreakfalse, etc etc.
% \begin{macrocode}
\if@inlabel
\global\@inlabelfalse
% \end{macrocode}
% The paragraph indent is now removed by using |\setbox...| since
% this makes |\noindent| a no-op here, as it should be. Thus the
% following comment is redundant but is left here for the sake of
% future historians:
% this next command was changed from an hskip to a kern to avoid
% a break point after the parindent box: the skip could cause a
% line-break if a very long label occurs in raggedright setting.
% \changes{v1.0d}{1994/05/03}{\cs{hskip} changed to \cs{kern}}
% \changes{v1.0m}{1996/10/23}{\cs{kern...} changed to \cs{setbox...}}
% \changes{v1.0r}{1997/02/21}
% {\cs{ifvoid} check added for \cs{noindent}. latex/2414}
% If |\noindent| was used after |\item| want to cancel the |\itemindent|
% skip. This case can be detected as the indentation box will be void.
% \begin{macrocode}
{\setbox\z@\lastbox
\ifvoid\z@
\kern-\itemindent
\fi}%
% \end{macrocode}
%
% \begin{macrocode}
\box\@labels
\penalty\z@
\fi
% \end{macrocode}
% This code is intended to prevent a page break after the first
% line of an item that comes immediately after a section title. It
% may be sensible to always forbid a page break after one line of
% an item? As with all such settings of |\clubpenalty| it is local
% so will have no effect if the item starts in a group.
%
% Only resetting |\@nobreak| when it is true is now
% essential since now it is sometimes set locally.
% \changes{v1.0m}{1996/10/23}{Added setting of \cs{clubpenalty} and
% set \cs{@nobreakfalse} only when necessary}
% \begin{macrocode}
\if@nobreak
\@nobreakfalse
\clubpenalty \@M
\else
\clubpenalty \@clubpenalty
\everypar{}%
\fi}%
% \end{macrocode}
% \changes{v1.0l}{1996/07/26}{Remove unecessary \cs{global} before
% \cs{@nobreak...}}
% \changes{v1.0m}{1996/10/23}{\cs{@nobreak...} moved into the
% \cs{everypar} and not executed unconditionally, see above}
% \begin{macrocode}
\if@noitemarg
\@noitemargfalse
\if@nmbrlist
% \end{macrocode}
% \changes{v1.0g}{1995/05/17}{Removed surplus braces}
% \begin{macrocode}
\refstepcounter\@listctr
\fi
\fi
% \end{macrocode}
% We use |\sbox| to support colour commands.
% \changes{LaTeX2e}{1993/12/08}{use \cs{sbox} to support colour}
% \begin{macrocode}
\sbox\@tempboxa{\makelabel{#1}}%
\global\setbox\@labels\hbox{%
\unhbox\@labels
\hskip \itemindent
\hskip -\labelwidth
\hskip -\labelsep
\ifdim \wd\@tempboxa >\labelwidth
\box\@tempboxa
% \end{macrocode}
% \changes{LaTeX2.09}{1991/11/22}
% {(RmS) Changed second call to \cs{makelabel} to
% \cs{unhbox}\cs{@tempboxa}.
% Avoids problems with side effects in \cs{makelabel} and is
% more efficient.}
% \begin{macrocode}
\else
\hbox to\labelwidth {\unhbox\@tempboxa}%
\fi
\hskip \labelsep}%
\ignorespaces}
% \end{macrocode}
% \end{macro}
%
% \begin{macro}{\makelabel}
% \changes{LaTeX2.09}{1991/11/04}
% {(RmS) added default definition for \cs{makelabel},
% to produce an error message.}
% \begin{macrocode}
\def\makelabel#1{%
\@latex@error{Lonely \string\item--perhaps a missing
list environment}\@ehc}
% \end{macrocode}
% \end{macro}
%
% \begin{macro}{\@nbitem}
% \changes{v1.0g}{1995/05/17}{Removed surplus braces}
% \begin{macrocode}
\def\@nbitem{%
\@tempskipa\@outerparskip
\advance\@tempskipa -\parskip
\addvspace\@tempskipa}
% \end{macrocode}
% \end{macro}
%
% \begin{macro}{\usecounter}
% \begin{macrocode}
\def\usecounter#1{\@nmbrlisttrue\def\@listctr{#1}\setcounter{#1}\z@}
% \end{macrocode}
% \end{macro}
%
%
% \subsection{Itemize and Enumerate}
%
% Enumeration is done with four counters: |enumi|, |enumii|, |enumiii|
% and |enumiv|, where |enum|N controls the numbering of the Nth level
% enumeration. The label is generated by the commands
% \cs{labelenumi} \ldots{} \cs{labelenumiv}, which should be defined
% by the document style.
% Note that \cs{p@enum}N\cs{theenum}N defines the output
% of a \cs{ref} command. A typical definition might be:
% \begin{verbatim}
% \def\theenumii{\alph{enumii}}
% \def\p@enumii{\theenumi}
% \def\labelenumii{(\theenumii)}
% \end{verbatim}
% which will print the labels as `(a)', `(b)', \ldots
% and print a \cs{ref} as `3a'.
%
% The item numbers are moved to the right of the label box, so they are
% always a distance of \cs{labelsep} from the item.
%
% \cs{@enumdepth} holds the current enumeration nesting depth.
%
% Itemization is controlled by four commands: \cs{labelitemi},
% \cs{labelitemii},
% \cs{labelitemiii}, and \cs{labelitemiv}.
% To cause the second-level list to be
% bulleted, you just define \cs{labelitemii}
% to be $\bullet$. \cs{@itemspacing}
% and \cs{@itemdepth} are the analogs of \cs{@enumspacing} and
% \cs{@enumdepth}.
%
% \begin{oldcomments}
% \enumerate ==
% BEGIN
% if \@enumdepth > 3
% then errormessage: ``Too deeply nested''.
% else \@enumdepth :=L \@enumdepth + 1
% \@enumctr :=L eval(enum@\romannumeral\the\@enumdepth)
% \list{\label(\@enumctr)}
% {\usecounter{\@enumctr}
% \makelabel{LABEL} == \hss \llap{LABEL}}
% fi
% END
%
% \endenumerate == \endlist
% \end{oldcomments}
%
% \begin{macro}{\@enumdepth}
% \begin{macrocode}
\newcount\@enumdepth \@enumdepth = 0
% \end{macrocode}
% \end{macro}
%
% \begin{macro}{\c@enumi}
% \begin{macro}{\c@enumii}
% \begin{macro}{\c@enumii}
% \begin{macro}{\c@enumiv}
% \begin{macrocode}
\@definecounter{enumi}
\@definecounter{enumii}
\@definecounter{enumiii}
\@definecounter{enumiv}
% \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
%
% \begin{environment}{enumerate}
% \changes{v1.0g}{1995/05/17}{Use \cs{thr@@} and remove surplus braces}
% \begin{macrocode}
\def\enumerate{%
\ifnum \@enumdepth >\thr@@\@toodeep\else
\advance\@enumdepth\@ne
\edef\@enumctr{enum\romannumeral\the\@enumdepth}%
% \end{macrocode}
%
% \changes{v1.0j}{1995/07/09}{Use \cs{expandafter}}
% \begin{macrocode}
\expandafter
\list
\csname label\@enumctr\endcsname
{\usecounter\@enumctr\def\makelabel##1{\hss\llap{##1}}}%
\fi}
% \end{macrocode}
%
% \begin{macrocode}
\let\endenumerate =\endlist
% \end{macrocode}
% \end{environment}
%
%
% \begin{oldcomments}
% \itemize ==
% BEGIN
% if \@itemdepth > 3
% then errormessage: 'Too deeply nested'.
% else \@itemdepth :=L \@itemdepth + 1
% \@itemitem == eval(labelitem\romannumeral\the\@itemdepth)
% \list{\@nameuse{\@itemitem}}
% {\makelabel{LABEL} == \hss \llap{LABEL}}
% fi
% END
%
% \enditemize == \endlist
%
% \end{oldcomments}
%
% \begin{macro}{\@itemdepth}
% \begin{macrocode}
\newcount\@itemdepth \@itemdepth = 0
% \end{macrocode}
% \end{macro}
%
% \begin{environment}{itemize}
% \changes{v1.0g}{1995/05/17}{Use \cs{thr@@}}
% \begin{macrocode}
\def\itemize{%
\ifnum \@itemdepth >\thr@@\@toodeep\else
\advance\@itemdepth\@ne
\edef\@itemitem{labelitem\romannumeral\the\@itemdepth}%
% \end{macrocode}
%
% \changes{v1.0j}{1995/07/09}{Use \cs{expandafter}}
% \begin{macrocode}
\expandafter
\list
\csname\@itemitem\endcsname
{\def\makelabel##1{\hss\llap{##1}}}%
\fi}
% \end{macrocode}
%
% \begin{macrocode}
\let\enditemize =\endlist
%</2ekernel>
% \end{macrocode}
% \end{environment}
%
% \Finale
%
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