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% booktabs.dtx
% Copyright (C) 1995--2020 Simon Fear
% Maintained by Danie Els <dnjels@gmail.com>
%
% This file is part of the booktabs package for publication
% quality tables for LaTeX
% -----------------------------------------------------------------
%
% This work may be distributed and/or modified under the conditions
% of the LaTeX Project Public License, either version 1.3c of this
% license or (at your option) any later version. The latest version
% of this license is in
% http://www.latex-project.org/lppl.txt
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% version 2008/05/04 or later.
%
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%<*package>
    [2020/01/12 v1.61803398 Publication quality tables]
%</package>
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\documentclass{ltxdoc}
  \usepackage{booktabs}[2020/01/12]
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%  \title{Publication quality tables in \LaTeX%
%        \thanks{This file has version number \fileversion,
%                (converging to phi, the golden ratio),
%                last revised \filedate.}}
% \author{Simon Fear\\300A route de Meyrin\\Meyrin\\Switzerland}
% \date{Printed \today}
%
% \maketitle
%
%
% \begin{abstract}
% This article describes some additional commands to enhance
% the quality of tables in \LaTeX. Guidelines are given as
% to what constitutes a good table in this context. The 2000
% release (Version 1.61) of the =booktabs= package, described
% herein, adds some enhancements to the 1995 release (Version 1.00),
% most notably =longtable= compatibility.
%
% Releases (Versions 1.618, 1.6180, 1.61803 and 1.618033) are
% only bug patches, support for the =colortbl= package and better
% compatability with =longtable=.\footnote{By Danie Els
%  (\texttt{dnjels@sun.ac.za}) in the absence of the author.}
% \end{abstract}
%
% \bigskip
%
% \section{Introduction}
%
% The routines described below are to enable the easy production
% of tables such as should appear in published scientific books and
% journals. What distinguishes these from plain
% \LaTeX{} tables is the default use of additional space above and below rules,
% and rules of varying `thickness'. What further distinguishes them from
% the tables many people {\em do} produce using \LaTeX{} is the
% absence of vertical rules and double rules.
%
% I must draw a clear
% distinction between what I call here a {\em formal table},
% which is a set of values in labelled columns, as distinct from
% what I will call a {\em tableau}. The latter is the kind of thing
% illustrated in the \LaTeX{} manual, and increasingly
% common as the output of
% many database management systems; it will probably have
% icons in abundance, and no doubt use colour too.
% The layout of such a {\em tableau} is determined
% (hopefully) as a one-off, given a jumble of material the
% designer is trying to combine into a meaningful configuration.
% But the layout of a {\em table} has been established over
% centuries of experience and should only be altered in
% extraordinary circumstances.
%
% By way of illustration, consider this tableau from the \LaTeX{}
% manual (p. 64 old edition):
%
% \begin{center}
% \begin{tabular}{||l|lr||} \hline
% gnats     & gram      & \$13.65 \\ \cline{2-3}
%           & each      & .01 \\ \hline
% gnu       & stuffed   & 92.50 \\ \cline{1-1} \cline{3-3}
% emu       &           & 33.33 \\ \hline
% armadillo & frozen    & 8.99 \\ \hline
% \end{tabular}
% \end{center}
%
% This is a hotch-potch of information that is probably
% reasonably clearly presented as is (but is the emu stuffed or
% not?). However, as a published table, this should
% much rather appear along the lines suggested
% further down the page in the manual:
%
% \begin{center}
% \begin{tabular}{@{}llr@{}} \toprule
% \multicolumn{2}{c}{Item} \\ \cmidrule(r){1-2}
% Animal & Description & Price (\$)\\ \midrule
% Gnat  & per gram  & 13.65 \\
%       & each      & 0.01 \\
% Gnu   & stuffed   & 92.50 \\
% Emu   & stuffed   & 33.33 \\
% Armadillo & frozen & 8.99 \\ \bottomrule
% \end{tabular}
% \end{center}
%
% It takes much less work to lay
% this out, as a formal table; we don't have to work out a new
% layout for everything we do. Moreover, we can be almost certain
% that the data cannot be misread, because the reader does not
% have to learn how to read some novel presentation.
%
% The above table cannot be produced in pure \LaTeX,
% unfortunately. It can be laid out as it should be, but despite
% your best efforts, using plain =\hline= commands produces
%
% \begin{center}
% \begin{tabular}{@{}llr@{}} \hline
% \multicolumn{2}{c}{Item} \\ \cline{1-2}
% Animal & Description & Price (\$)\\ \hline
% Gnat  & per gram  & 13.65 \\
%       & each      & 0.01 \\
% Gnu   & stuffed   & 92.50 \\
% Emu   & stuffed   & 33.33 \\
% Armadillo & frozen & 8.99 \\ \hline
% \end{tabular}
% \end{center}
%
% Note (if it is not already obvious) that there is not enough
% space between the top line and the capital I of `Item', and so
% on for all the lines: contrast with the previous version. Also, in
% the first version
% the top and bottom rules (ie lines) are
% heavier than the middle rule, which is turn heavier than the
% subrule underneath `Item'. Of course you \emph{could} redefine
% =\doublerulesep= and then use =\hline\hline= to get something
% near the same effect, and you could use struts to improve
% the spacing. But you should not have to
% think of such things. The =booktabs= style defines its commands so
% that such things are taken care of automatically.
%
% In general, I would say that
% this package is of no interest to those looking for
% an alternative to Pic\TeX{} to conjure up fancy tableaux.
% Rather, it is a style guide for authors of scientific papers
% and books as regards table layout. It is not going too far to
% say that if you cannot
% create a table using the commands in this package, you should
% redesign it.
%
% \subsection{A note on terminology\label{notation}}
%
% In British typesetting, a `line' is always called a `rule'. Perhaps
% confusingly (for historic reasons in fact), the `thickness' of
% rule is often referred to as is its `width' (whereas just about
% everyone else would call this `depth' or `height', if they were thinking
% of a horizontal rule). A `thick black line' is called a `heavy
% rule'. I have used this terminology in most of the new commands
% below. If nothing else it avoids confusion with =\hline=.
%
% \section{The layout of formal tables}
%
% You will not go far wrong if you remember two simple
% guidelines at all times:
% \begin{enumerate}
%   \item Never, ever use vertical rules.
%   \item Never use double rules.
% \end{enumerate}
% These guidelines may seem extreme but I have
% never found a good argument in favour of breaking them. For
% example, if you feel that the information in the left half of
% a table is so different from that on the right that it needs
% to be separated by a vertical line, then you should use two
% tables instead. Not everyone follows the second guideline:
% I have worked for a publisher who insisted on a
% double light rule above a row of totals. But this would not
% have been my choice.
%
% There are three further guidelines worth mentioning here as they
% are generally not known outside the circle of professional
% typesetters and subeditors:
% \begin{enumerate}\setcounter{enumi}{2}
%   \item Put the units in the column heading (not in the body of
%           the table).
%   \item Always precede a decimal point by a digit; thus 0.1
%       {\em not} just .1.
%   \item Do not use `ditto' signs or any other such convention to
%       repeat a previous value. In many circumstances a blank
%       will serve just as well. If it won't, then repeat the value.
% \end{enumerate}
%
% Whether or not you wish to follow the minor niceties,
% if you use only the following commands in your formal tables
% your reader will be grateful. I stress that
% the guidelines are not just to
% keep the pedantic happy. The principal is that enforced structure of
% presentation
% enforces structured thought in the first instance.
%
% \section{Use of the new commands}
%
% \DescribeMacro\toprule
% \DescribeMacro\midrule
% \DescribeMacro\bottomrule
% In the simplest of cases a table begins with a =\toprule=, has
% a single row of column headings, then a dividing rule called
% here a =\midrule=; after the columns of data we finish off with
% a =\bottomrule=. Most book publishers set the =\toprule= and
% =\bottomrule= heavier (ie thicker, or darker; see section \ref{notation})
% than the intermediate =\midrule=. However, when tables appear
% in very small typesizes it is sometimes impossible to make this
% distinction, and moreover quite a few journals routinely use all rules of
% the same heaviness.
%
% The rule commands here all take a default
% which may be reset within the document (preferably, but not
% necessarily, in the preamble). For the top and bottom rules this
% default
% is =\heavyrulewidth= and for midrules it is =\lightrulewidth=
% (fully described below). In very rare cases where you need to do
% something special, you may use the optional arguments to the rule
% commands which have formal syntax as follows:
% \begin{quote}
%   "\toprule["\meta{wd}"]" \\
%   "\midrule["\meta{wd}"]" \\
%   "\bottomrule["\meta{wd}"]"
% \end{quote}
% where \meta{wd} is a \TeX dimension (for example 1pt, .5em,
% etc.).
%
% All the rule commands described here go after the closing
% =\\= of the preceding row (except =\toprule=, which
% comes right after the =\tabular{}= command); in other words,
% exactly where plain \LaTeX{} allows =\hline= or =\cline=.
%
% \DescribeMacro\cmidrule
% Frequently we need a sub-rule to extend over only some of the columns,
% for which we need a =\cmidrule= (the analogue of \LaTeX's =\cline=
% command). Generally, this rule should not come to the full width of
% the columns, and this is especially the case when we need to begin
% a =\cmidrule= straight after the end of another one (\LaTeX's
% =\cline=s crash into each other here if you are not extra careful with
% =\extracolsep=).  Thus, you will generally want to use the optional
% `trimming' commands.
%
% The trimming commands, if used at all, go in
% parentheses (like this), with no spaces separating them. The possible
% specifications are =r=, =r{=\meta{wd}=}=, =l= and
% =l{=\meta{wd}=}=, or any combination of these, where \meta{wd} is a
% dimension, and =r= and =l= indicate whether the right and/or left ends
% of the rule should be trimmed. The form without explicit argument is
% equivalent to =r{\cmidrulekern}=, where =\cmidrulekern= defaults to
% $0.5$ em, but can be set by the user in the preamble.\footnote{User
%   feedback suggested the Version 1.00 default, 0.25 em, was too
%   small. Sorry for any loss of backward compatibility. Remember that
% you
%   can easily set \texttt{\textbackslash cmidrulekern} in the preamble, or just use
%   \texttt{(r\{.25em\})} to recover the original behaviour.}
%
% Here's an illustrative example: =(lr{.75em})= gives you a default
% left trim and exactly $0.75$ em right trim. Equally valid here is
% =(r{.75em}l)=.\footnote{As a matter of fact, \texttt{(lrrlr\{.75em\})}
% does the same thing: only the
% last encountered left and the last encountered right specification
% are applied.}
%
% The full syntax of the command is
% \begin{quote}
%   "\cmidrule["\meta{wd}"]("\meta{trim}"){"$a$--$b$"}"
% \end{quote}
% where \meta{wd} is an optional rule width command, in square
% brackets [like this] (the
% default here is =\cmidrulewidth=), and the last argument, \emph{which
% is not optional}, gives the column numbers to be spanned.
%
% An example of the commands in use is given by the code used to
% produce the example table above:
% \begin{verbatim}
% \begin{tabular}{@{}llr@{}} \toprule
% \multicolumn{2}{c}{Item} \\ \cmidrule(r){1-2}
% Animal & Description & Price (\$)\\ \midrule
% Gnat  & per gram  & 13.65 \\
%       & each      & 0.01 \\
% Gnu   & stuffed   & 92.50 \\
% Emu   & stuffed   & 33.33 \\
% Armadillo & frozen & 8.99 \\ \bottomrule
% \end{tabular}
% \end{verbatim}
%
% \DescribeMacro\addlinespace
% Occasionally we want to put an extra space between certain rows
% of a table; for example, before the last row, if this is a
% total. This is simply a matter of inserting
% \begin{quote}
%   "\addlinespace["\meta{wd}"]"
% \end{quote}
%  after the =\\= alignment marker. Between ordinary rows of text, the
%  effect is identical to the ordinary \LaTeX\ usage
%  =\\[\defaultaddspace]=, which I find rather clumsy, and it is better
%  than =\\ \\=, which inserts too much space. Also,
%  =\addlinespace= can be used before, after, or between rules if you
%  want to control the exact amount of space to be inserted. The default
%  space before or after an adjacent rule is replaced by exactly
%  =\defaultaddspace= or the amount of
%  space specified in the optional argument.\footnote{This is a change
% from version 1.00, where the space was sometimes \emph{in addition
% to} default rule space.}
%
% \section{Abuse of the new commands}
%
% Let's face it, nobody can leave well alone, so here are some
% guidelines and extra commands.
%
% The new rule commands are not guaranteed to work with =\hline=
% or =\cline=, although these remain available and unchanged. I
% cannot foresee any reason to want to mix them.
%
% More importantly the rules generated by the new commands are in
% no way guaranteed to connect with verticals generated by ={|}=
% characters in the preamble. This is a feature (see above). You
% should not use vertical rules in tables, end of story.
%
% \DescribeMacro\morecmidrules
% If you just cannot stop yourself from using a double rule,
% even a construction as bizarre as =\toprule\bottomrule\midrule=
% will work without generating an error message (just as you can
% double =\hline=). These rules will be separated by the ordinary
% \LaTeX\ separator =\doublerulesep=. However if your perversion
% is to want double =\cmidrule=s you will need the extra command
% =\morecmidrules= to do so properly, because normally two
% =\cmidrule=s  in a row is a sane construction
% calling for two rules on the same `rule row'. Thus in
% \begin{quote}
%   "\cmidrule{1-2}\cmidrule{1-2}"
% \end{quote}
% the second command writes a rule that just overwrites the first
% one; I suppose you wanted
% \begin{quote}
%   "\cmidrule{1-2}\morecmidrules\cmidrule{1-2}"
% \end{quote}
% which gives you a double rule between columns one and two,
% separated by =\cmidrulesep= (note: since a =\cmidrule= is
% generally very light, the ordinary =\doublerulesep= is probably
% too much space). Finish off a whole row of rules before giving the
% =\morecmidrules= command. Note that =\morecmidrules= has no
% effect whatsoever if it does not immediately follow a
% =\cmidrule= (ie it is not a general space-generating command).
%
% \DescribeMacro\specialrule
% If you find some extraordinary need to specify exactly $0.5$ em, say, between two
% rules, you could use a construction such as =\midrule =
% =\addlinespace[.5em] \midrule=. In a rare fit of tolerance, though,
% I have also
% provided the command
% \begin{quote}
%   "\specialrule{"\meta{wd}"}{"\meta{abovespace}"}{"\meta{belowspace}"}"
% \end{quote}
% where all three arguments are mandatory (I couldn't be bothered to
% program in defaults). If you use this frequently, you have
% misunderstood the purpose and content of the guidelines given above. A
% preceeding rule does not add its default space below, and a following
% rule adds no space above itself, so you get \emph{exactly} the space
% specified in the arguments.\footnote{This is a change from Version 1.00,
% which rather liked to add an extra \texttt{\textbackslash doublerulesep} space whenever it
% could.}
%
%
% \section{Booktabs and longtables}
%
% If you have both =booktabs= and =longtable= packages loaded, the
% =booktabs= rule commands can now all be used exactly as described
% above, within a longtable.
%
% There is an addition worth noting: within a =longtable=, you can use
% the optional left and right trimming commands, which normally only
% work for =\cmidrule=s, with =\toprule=, =\midrule= and =\bottomrule=
% (and if you must, also with =\specialrule=). Users who hacked the
% previous release for longtable compatability\footnote{Jim Service was
% the first} seemed to like all the rules to be right trimmed 0.5 em. I
% think you can do the same by making =@{}= be the last column
% specifier. Still, after working out the rest of the code, it was easy
% to add parsing for the optional arguments, so I did. (I didn't go the
% whole way and allow the optional trimming \emph{outside} a
% =longtable=; this would be a huge amount of work. If you must have
% trimmed rules, make all your tables be =longtable=s!)
%
% A somewhat technical note: within a =longtable=, =\hline= and
% =\hline\hline= both produce a \emph{double} rule (to allow for page
% breaks occurring at that point). But the =booktabs= rules do
% \emph{not}. Longtable's automatic doubling of =\hline= is
% questionable, even according to the documentation within that
% package. But doubled =booktabs= rules make almost no sense at all. In
% the unfortunate event that a =booktabs= rule should occur at a page
% break, then you will have to make the necessary adjustments by
% hand.\footnote{Fixed in version  1.618033 (Morten H{\o}gholm)}
% (In general, this will mean deleting the offending rule.)
%
%
% \section{Booktabs and and the colortbl package}
%
%  =Booktabs= is now compatible with the =colortbl= package.\footnote{Since v1.6180}
%  The \cmd{\arrayrulecolor} command will result in coloured
%  rules if the =colortbl= package is loaded.
%
%
% \section{Technical summary of commands}
%
% The new rule commands are valid inside the standard =tabular= (and
% =array=) environment, in the modified =tabular= and =array= of
% =\usepackage{array}=, and within both standard tables and longtables
% after =\usepackage{longtable}=.
%
% The commands follow the standard placement syntax of =\hline=.
% There can be space (including carriage-return,
% but not two carriage-returns) between successive
% rule commands.\footnote{A welcome change from Version 1.00, where space between
% rule commands generated a very baffling error message.}
%
% In what amounts to quite a big change from former releases, within
% the macro code I now define three classes of rules. (But we don't need these
% definitions within ordinary use, so I haven't even mentioned them above.)
% A class 1 rule (otherwise called a `normal' rule) is any of
% =\toprule=, =\midrule=, =\bottomrule=, or =\cmidrule=. The class 2
% rules are =\specialrule= and =\addlinespace=. Finally, a class 0 rule
% is none of the preceeding --- or in other words, not a rule at
% all.\footnote{Except that \texttt{\textbackslash hline} and
% \texttt{\textbackslash cline} are class 0. Still, there
%   is no reason to lose sleep over this, since one would not want to mix
%   the two rule-drawing systems.} Note that =\addlinespace= counts as a
% class 2 rule, not as class 0 text.
%
% In the following, we first describe each command in `normal use', meaning
% that the rule is being used between two lines of text (or more
% technically, is preceded and followed by a class 0 rule). After that,
% we will look at the exceptions.
% \begin{quote}
%   "\toprule["\meta{wd}"]"
% \end{quote}
% A rule of width \meta{wd} (default =\heavyrulewidth=) with
% =\abovetopsep= space above and
% =\belowrulesep= extra vertical space inserted below it. By default,
% =\abovetopsep= is zero, which seems sensible for a rule designed to
% go at the top. However, if your
% tables have captions, it can make sense to use =\abovetopsep= to
% insert a reasonable amount of space between caption and table,
% rather than remember to use a =\vspace{}= command in the float.
% \begin{quote}
%   "\midrule["\meta{wd}"]"
% \end{quote}
% A \meta{wd} (default =\lightrulewidth=) rule with
% =\aboverulesep= space above it and
% with =\belowrulesep= space below it.
% \begin{quote}
%   "\bottomrule["\meta{wd}"]"
% \end{quote}
% A \meta{wd} (default =\heavyrulewidth=) rule with =\aboverulesep=
% space above it and with =\belowbottomsep= space below it. By default
% =\belowbottomsep= is zero\footnote{This is a change from Version 1.00,
% where there was always a \texttt{\textbackslash belowrulesep}}.
% There is a frequent and legitimate reason
% you might want space below a bottom rule: namely, when there's a table
% footnote.\footnote{But don't use footnotes, Donald.}
% If you don't override the default you could use
% =\bottomrule \addlinespace[\belowrulesep]=
% or you could put a suitably sized strut
% into the footnote text.\footnote{I don't like either of these. Sort it out in
% Version 1.618?} But the default has to be zero, so that it behaves
% sensibly in a =longtable= footer.
% \begin{quote}
%   "\cmidrule["\meta{wd}"]("\meta{trim}"){"$a$--$b$"}"
% \end{quote}
% A \meta{wd} (default =\cmidrulewidth=) rule with
% =\aboverulesep= space above it (unless following another
% =\cmidrule=, in which case it is on the same vertical alignment; or
% if following =\morecmidrules=, separated from a previous =\cmidrule=
% by =\cmidrulesep=). A =\cmidrule= has
% =\belowrulesep= below it (unless followed by another
% =\cmidrule=, in which case the following rule is on the same
% vertical alignment; or if followed by =\morecmdirules=, when there
% will be
% =\cmidrulesep= below it).
%
% The =\cmidrule= spans columns $a$ to $b$ as specified in the mandatory
% argument. The optional argument \meta{trim}, which goes in parentheses
% if at all, can contain any sequence of the tokens =r=, =l= and
% ={=\meta{wd}=}=, with the latter setting the kerning to be applied to
% right or left sides as specified by the immediately preceding token.
% (There's currently no error checking done here, so be careful to get
% the syntax right.)
% \begin{quote}
%   "\morecmidrules"
% \end{quote}
% Instructs \LaTeX\ to begin a new row of =\cmidrules=,
% separated from the last by =\cmidrulesep=. Has no meaning
% in any other context.
% \begin{quote}
%   "\specialrule{"\meta{wd}"}{"\meta{abovespace}"}{"\meta{belowspace}"}"
% \end{quote}
% A \meta{wd} rule (note: here this is a mandatory argument) with
% \meta{abovespace} above it and \meta{belowspace} below it.
% \begin{quote}
%   "\addlinespace["\meta{wd}"]"
% \end{quote}
% Technically this has the same effect as
% =\specialrule{0pt}{0pt}{=\meta{wd}=}=, i.e. a zero-width rule with no
% space above and with \meta{wd} (default =\defaultaddspace=) space
% below. This command was primarily designed to add space between rows
% in the body of the table, but it may also be used to specify an exact
% amount of space above or below a class 1 rule.
%
% \vspace{1em}
% Now we come to the exceptions to the above. We have already seen in
% the definitions that the type 2 rules are preceded and followed by
% exactly the amount of space specified by the arguments. That is, a
% type 2 rule suppresses the space that would normally be generated by a
% previous type 1 rule (e.g. =\belowrulesep= after a =\toprule=) and
% replaces it by the argument of the type 2 rule. Similarly, in the
% combination \{type 2 rule\}\{type 1 rule\}, the ordinary space above
% the type 1 rule (e.g. =\aboverulesep=) is suppressed. But in the
% combination \{type 2 rule\}\{type 2 rule\}, no space is suppressed:
% the rules will be separated by both the first rule's
% ={=\meta{belowspace}=}= and the second rule's ={=\meta{abovespace}=}=
% arguments. Last but not least, the combination \{type 1 rule\}\{type 1
% rule\} will always give rules separated by =\doublerulesep=,
% suppressing all normal space generated between the rules (but
% retaining normal space above the first and below the second).
%
% As an exception to this last exception, `type 1 rule' excludes
% =\cmidrule=. Such rules combine with other =\cmidrule=s and
% =\morecmidrules= in normal use as described above. I don't know and
% I don't care
% care what the combination =\toprule\cmidrule{1-2}\midrule= would
% produce. I can see no excuse for such usage.
%
%\vspace{1em}
% The default dimensions are defined at the beginning of the macro
% description section (Section \ref{code}). The user can change
% these defaults in the preamble, or outside a
% tabular environment, by simply
% inserting a command in exactly the same format as in Section \ref{code}; the
% redefinition will stay in effect for the rest of the document
% or until redefined again. \emph{Inside a table} you would have to make the
% assignment globally in a =noalign= group:
% e.g. \verb|\noalign\{\global\abovetopsep=1em\toprule}|. I hope
% you never have to do that.
%
% \section{Acknowledgments}
% Hugely indebted of course to DEK and Lamport; the optional
% argument and =\cmidrule=
% stuff especially was stolen from =latex.sty=.
% The documentation driver stuff is stolen from the
% tools package description =dcolumn.dtx= by David Carlisle.
%
% For beta testing and encouragement ...
%
% \StopEventually
%
% \section{The code\label{code}}
%
%    The current version is defined at the top of the file looking
%    something like this
%    \begin{macrocode}
%<*package>
%\NeedsTeXFormat{LaTeX2e}
%\ProvidesPackage{booktabs}
%        [\filedate\space version\fileversion]
%    \end{macrocode}
%
% First we set up the new dimensions described above:
%    \begin{macrocode}
\newdimen\heavyrulewidth
\newdimen\lightrulewidth
\newdimen\cmidrulewidth
\newdimen\belowrulesep
\newdimen\belowbottomsep
\newdimen\aboverulesep
\newdimen\abovetopsep
\newdimen\cmidrulesep
\newdimen\cmidrulekern
\newdimen\defaultaddspace
\heavyrulewidth=.08em
\lightrulewidth=.05em
\cmidrulewidth=.03em
\belowrulesep=.65ex
\belowbottomsep=0pt
\aboverulesep=.4ex
\abovetopsep=0pt
\cmidrulesep=\doublerulesep
\cmidrulekern=.5em
\defaultaddspace=.5em
%    \end{macrocode}
% And some internal counters of no interest to the end user:
% \changes{v1.618}{2003/03/28}{Remove \cs{@cmidrulewidth} }
%    \begin{macrocode}
\newcount\@cmidla
\newcount\@cmidlb
\newdimen\@aboverulesep
\newdimen\@belowrulesep
\newcount\@thisruleclass
\newcount\@lastruleclass
\@lastruleclass=0
\newdimen\@thisrulewidth
%    \end{macrocode}
% which will be described as needed below.
%
% \begin{macro}{\futurenonspacelet}
% Next we define a very useful macro (more-or-less straight from the
% \TeX book's Dirty Tricks chapter; documented there). Use
% =\futurenonspacelet= instead of =\futurelet= when looking for the next
% (non-space) token after a macro that has an argument. (After a macro
% without an argument, space is ignored anyway, so =\futurenonspacelet=
% wouldn't be needed.) This hack allows users to type white
% space between successive rule commands (which did not work in Version
% 1.00).
%    \begin{macrocode}
\def\futurenonspacelet#1{\def\@BTcs{#1}%
   \afterassignment\@BTfnslone\let\nexttoken= }
\def\@BTfnslone{\expandafter\futurelet\@BTcs\@BTfnsltwo}
\def\@BTfnsltwo{\expandafter\ifx\@BTcs\@sptoken\let\next=\@BTfnslthree
   \else\let\next=\nexttoken\fi \next}
\def\@BTfnslthree{\afterassignment\@BTfnslone\let\next= }
%    \end{macrocode}
% \end{macro}
%
% \subsection{Full width  rules}
%
% When we are not in a =longtable= environment, we can simply
% implement the full width rules as a =\hrule= in  a =\noalign{}=
% group. But within a =longtable=, the rule has to be drawn like a
% =\cmidrule{1-\LT@cols}= (the rationale for this is explained in the
% =longtable= documentation).
%
% In order to allow for both, all the rule macros have to
% open a =\noalign= group immediately, while they work out whether
% they have been called within a =longtable=; if you don't do this,
% \TeX's underlying =\halign= process gets hiccups.
% I use \LaTeX's
% dirty trick (\verb?\ifnum=0`}?) to fool the parser that the bracket
% count is OK. The bracket really gets closed after all the skipping
% at the end of the =\@BTendrule= macro.
%
% The class 1 rules, and =\specialrule=, really only differ in the
% defaults for space above and
% below, and the width, passed to a common routine, =\@BTrule=,
% described below. The spaces, =\@aboverulesep= and =\@belowrulesep=,
% are set within the =\noalign= group, so are inherited by
% =\@BTrule=. Similarly, =\@BTrule= knows as much as it needs to
% about the routine that called it by examining the inherited
% =\@thisruleclass=. The optional width argument is parsed by
% =\@BTrule= after being set to default if absent.
%
%
% \begin{macro}{\toprule}
% \changes{v1.61803}{2005/04/14}{Change \cmd{\@belowrulesep} to \cmd{\belowrulesep}}
% \begin{macro}{\midrule}
% \begin{macro}{\bottomrule}
% \begin{macro}{\specialrule}
%    \begin{macrocode}
\def\toprule{\noalign{\ifnum0=`}\fi
  \@aboverulesep=\abovetopsep
  \global\@belowrulesep=\belowrulesep %global cos for use in the next noalign
  \global\@thisruleclass=\@ne
  \@ifnextchar[{\@BTrule}{\@BTrule[\heavyrulewidth]}}
\def\midrule{\noalign{\ifnum0=`}\fi
  \@aboverulesep=\aboverulesep
  \global\@belowrulesep=\belowrulesep
  \global\@thisruleclass=\@ne
  \@ifnextchar[{\@BTrule}{\@BTrule[\lightrulewidth]}}
\def\bottomrule{\noalign{\ifnum0=`}\fi
  \@aboverulesep=\aboverulesep
  \global\@belowrulesep=\belowbottomsep
  \global\@thisruleclass=\@ne
  \@ifnextchar[{\@BTrule}{\@BTrule[\heavyrulewidth]}}
\def\specialrule#1#2#3{\noalign{\ifnum0=`}\fi
  \@aboverulesep=#2\global\@belowrulesep=#3\global\@thisruleclass=\tw@
  \@BTrule[#1]}
%    \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \begin{macro}{\addlinespace}
% An =\addlinespace= is essentially a zero-width rule with
% zero space above and argument (or default) space below. But because
%  the rule is not actually drawn, but is just a =\vskip=, there is no
%  need to check if we're in a longtable, so we don't need to call
%  =\@BTrule= as for `real' rules. But we do share the =\@BTendrule=
%  lookahead and flagsetting code (described below), and the =\vskip= is done there.
%    \begin{macrocode}
\def\addlinespace{\noalign{\ifnum0=`}\fi
  \@ifnextchar[{\@addspace}{\@addspace[\defaultaddspace]}}
\def\@addspace[#1]{\global\@belowrulesep=#1\global\@thisruleclass=\tw@
  \futurelet\@tempa\@BTendrule}
%    \end{macrocode}
% \end{macro}
%
%
% \begin{macro}{\@BTrule}
% All the rules (except =\addlinespace=) share this code.
% \changes{v1.618033}{2016/04/27}{Rearranged and added \cmd{\nobreak} within longtable (Morten H{\o}gholm)}
% \changes{v1.6180339}{2019/10/08}{Add test for xltabular (Herbert Voss)}
% \changes{v1.61803398}{2020/01/12}{Restore \cmd{\@BTrule} to v1.618033 (Danie Els) }
%    \begin{macrocode}
\def\@BTrule[#1]{%
%    \end{macrocode}
%  Now we work out, by a very nasty hack, if we're within a
%  =longtable=. It's easy if =\longtable= isn't even defined: then we
%  can't be. But it is not enough just to check if =longtable= is
%  loaded --- we might be within an ordinary table rather than a
%  longtable. So we look to see if =\hline= has been re-defined
%  from its \LaTeX\ definition to be the same as
%  =\LT@hline=. (Longtable currently does this redefinition when it opens a
%  =longtable= environment, but not globally, so it is
%  cleared it when the environment closes.) Another
%  package could potentially do this! And =longtable= might change the
%  way it implements this! So, it is not entirely safe, but I have
%  found no better way so far.
%
%  We set up =\@BTswitch= to call =\@BTnormal= or =\@BLTrule=, as
%  appropriate, then call it.
%    \begin{macrocode}
  \ifx\longtable\undefined
    \let\@BTswitch\@BTnormal
  \else\ifx\hline\LT@hline
    \nobreak
    \let\@BTswitch\@BLTrule
  \else
    \let\@BTswitch\@BTnormal
  \fi\fi
%    \end{macrocode}
% Call =\@BTswitch= at end of macro
%    \begin{macrocode}
  \global\@thisrulewidth=#1\relax
%    \end{macrocode}
% Save the width argument (if the user didn't give one, then the
% calling routine will have called =\@BTrule= with the default) in a global
% variable for later use when drawing the rule.
%    \begin{macrocode}
  \ifnum\@thisruleclass=\tw@\vskip\@aboverulesep\else
%    \end{macrocode}
% Specialrules always insert specified space above. (Note: addlinespaces
% don't come here).
%    \begin{macrocode}
  \ifnum\@lastruleclass=\z@\vskip\@aboverulesep\else
  \ifnum\@lastruleclass=\@ne\vskip\doublerulesep\fi\fi\fi
%    \end{macrocode}
% After text (last rule class 0), precede the rule by =\aboverulesep=;
% but if immediately after a
% previous rule, insert a =\doublerulesep=.
%
%    \begin{macrocode}
  \@BTswitch}
%    \end{macrocode}
% \end{macro}
%
%
% \begin{macro}{\CT@arc@}
%   \changes{v1.6180}{2005/03/16}{add colortbl command for color support}
%   This is support for the colortbl package for colored
%   rules.  \cmd{\CT@arc@} hold the \cmd{\arrayrulecolor} setting.
%    \begin{macrocode}
\AtBeginDocument{%
   \providecommand*\CT@arc@{}}%% colortbl support
%    \end{macrocode}
% \end{macro}
%
%
% \begin{macro}{\@BTnormal}
%   \changes{v1.6180}{2005/03/16}{add colortbl \cmd{\CT@arc@} command for color support}
% This is when we're \emph{not} within a longtable. We are already in a
%  =\noalign= group, all we need do is draw an =\hrule= and gobble any
%  trailing spaces, then call the closing routine with =\@tempa= set
%  equal to the next token in the document.
%
%    \begin{macrocode}
\def\@BTnormal{%
    {\CT@arc@\hrule\@height\@thisrulewidth}%
    \futurenonspacelet\@tempa\@BTendrule}
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\@BLTrule}
% This is for full width rule within a =longtable=. First we check if
%  a kerning argument has been used; if so let =\@@BLTrule= read it,
%  else call =\@@BLTrule= with an empty string:
%    \begin{macrocode}
\def\@BLTrule{\@ifnextchar({\@@BLTrule}{\@@BLTrule()}}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\@@BLTrule}
%    \begin{macrocode}
\def\@@BLTrule(#1){\@setrulekerning{#1}%
\global\@cmidlb\LT@cols
%    \end{macrocode}
% The =\@setrulekerning= routine parses the kerning argument tokens
% and sets global kerning widths accordingly (or to defaults, if user
% hasn't set them explicitly). The global assignment to =\@cmidlb=
% sets up the column count for the =\@cmidruleb= macro, which is
% shared with =cmidrules=.
%    \begin{macrocode}
\ifnum0=`{\fi}%
%    \end{macrocode}
% Close the currently open =\noalign= group. Within a =longtable=,
% rules are all to be drawn as leaders within a text box that is
% =\LT@cols= columns wide.
%    \begin{macrocode}
\@cmidruleb
%    \end{macrocode}
% Draw the rule. We share the =\@cmidruleb= code with ordinary =\cmidrule=s.
%    \begin{macrocode}
\noalign{\ifnum0=`}\fi
%    \end{macrocode}
% We have to open a new noalign immediately else \TeX will start a new
%    text box where we don't want one. Then, after gobbling any
%    unwanted white space, we call the closing routine.
%    \begin{macrocode}
\futurenonspacelet\@tempa\@BTendrule}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\@BTendrule}
% We look one step ahead (token is in =\@tempa=) to see if another
% rule follows (shame on user!). If so, we set =\@lastruleclass= equal
% to =\@thisruleclass= (thus setting it up for the following rule). If
% there isn't a following rule, we clear =\@lastruleclass= (ie set it
% to zero), which isn't technically true since we have just drawn a
% rule, but sets it up correctly for the next rule encountered, which
% must be following some intervening text.
%    \begin{macrocode}
\def\@BTendrule{\ifx\@tempa\toprule\global\@lastruleclass=\@thisruleclass
  \else\ifx\@tempa\midrule\global\@lastruleclass=\@thisruleclass
  \else\ifx\@tempa\bottomrule\global\@lastruleclass=\@thisruleclass
  \else\ifx\@tempa\cmidrule\global\@lastruleclass=\@thisruleclass
  \else\ifx\@tempa\specialrule\global\@lastruleclass=\@thisruleclass
  \else\ifx\@tempa\addlinespace\global\@lastruleclass=\@thisruleclass
  \else\global\@lastruleclass=\z@\fi\fi\fi\fi\fi\fi
  \ifnum\@lastruleclass=\@ne\relax\else\vskip\@belowrulesep\fi
  \ifnum0=`{\fi}}
%    \end{macrocode}
% \end{macro}
%
%
% \subsection{Special subrules}
%
% \begin{macro}{\@setrulekerning}
% The following code parses the trimming arguments (if there are any)
%    for =\cmidrule= or a =\BLTrule=. The rule
%     will be trimmed left and right by =\cmrkern@l= and =\cmrkern@l=,
%     which are zero by default, set to =\cmidrulekern= by the plain
%     =(lr)= arguments, or user set as in =(r{.5em})=. We parse token by
%     token through the arguments. The
%     tokens =r= and =l= cause =\cmrkern@r= or =\cmrkern@l= to be set to
%     =\cmidrulekern=. There is no lookahead to see if a width is the
%     next token; this strategy is efficient for the plain commands,
%     while inefficient for the qualified commands, but more importantly
%     it is much easier to program. Tokens =r= and =l= also set
%     =\cmrswitch= so that if the next token turns out to be
%     ={=\meta{wd}=}= then the kerning will be done on the side
%     currently specified. I have been too lazy to program an error
%     message should one encounter tokens other than =r=, =l= or
%     ={=\meta{wd}=}=.
% \changes{v1.6180}{2005/03/16}{Refine option testing in \cmd{\@setrulekerning}}
%    \begin{macrocode}
\def\@setrulekerning#1{%
   \global\let\cmrkern@l\z@
   \global\let\cmrkern@r\z@
   \@tfor\@tempa :=#1\do
  {\def\@tempb{r}%
   \ifx\@tempa\@tempb
      \global\let\cmrkern@r\cmidrulekern
      \def\cmrsideswitch{\cmrkern@r}%
   \else
      \def\@tempb{l}%
      \ifx\@tempa\@tempb
         \global\let\cmrkern@l\cmidrulekern
         \def\cmrsideswitch{\cmrkern@l}%
      \else
         \global\expandafter\let\cmrsideswitch\@tempa
      \fi
   \fi}}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\cmidrule}
% \begin{macro}{\@cmidrule}
% \begin{macro}{\@@cmidrule}
% \begin{macro}{\@@@cmidrule}
% The =\cmidrule= re-uses =\@lastruleclass= in an entirely different
%  way from the full width rules. (Maybe I should have used a
%  different flag; it seemed efficient at the time \ldots). This
% is (left) set to one if you are in the middle of a row of
% =\cmidrules=, or starting a new one (with =\morecmidrules=).
% Otherwise, when =\@lastruleclass= is zero, we precede the
% rule with =\aboverulesep=.
%    \begin{macrocode}
\def\cmidrule{\noalign{\ifnum0=`}\fi
    \@ifnextchar[{\@cmidrule}{\@cmidrule[\cmidrulewidth]}}
\def\@cmidrule[#1]{\@ifnextchar({\@@cmidrule[#1]}{\@@cmidrule[#1]()}}
\def\@@cmidrule[#1](#2)#3{\@@@cmidrule[#3]{#1}{#2}}
%    \end{macrocode}
% The above is fiddling around to set defaults for missing optional
% arguments. We also pass to =\@@@cmidrule= in a different order,
% namely =[a-b]=={width required}= ={kerning commands}= (this being
% the order in which the arguments are actually processed):
%    \begin{macrocode}
\def\@@@cmidrule[#1-#2]#3#4{\global\@cmidla#1\relax
    \global\advance\@cmidla\m@ne
    \ifnum\@cmidla>0\global\let\@gtempa\@cmidrulea\else
    \global\let\@gtempa\@cmidruleb\fi
    \global\@cmidlb#2\relax
    \global\advance\@cmidlb-\@cmidla
%    \end{macrocode}
% This has set up a switch (=\@gtempa=) to call the relevant routine,
% =\@cmidrulea= or =\@cmidruleb=, depending on whether we start
% from column one or not.
%    \begin{macrocode}
    \global\@thisrulewidth=#3
%    \end{macrocode}
% That is, set per default or given argument. Then parse any trimming
% arguments to set, globally, =\cmrkern@r= and =\cmrkern@l= accordingly:
%    \begin{macrocode}
    \@setrulekerning{#4}
%    \end{macrocode}
% Now insert space above if needed, close the =\noalign=,
% then switch to appropriate rule drawing routine as determined
% above (=\let= to =\@gtempa=):
%    \begin{macrocode}
    \ifnum\@lastruleclass=\z@\vskip \aboverulesep\fi
    \ifnum0=`{\fi}\@gtempa
%    \end{macrocode}
% Having now drawn the rule,
% open another =\noalign=, and call the closing routine:
%    \begin{macrocode}
    \noalign{\ifnum0=`}\fi\futurenonspacelet\@tempa\@xcmidrule}
%    \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
%
% \begin{macro}{\@xcmidrule}
% In this closing routine, see if another =\cmidrule= follows;
% if so, backspace
% vertical so it will line up with the one you just drew,
% and setting =\@lastruleclass= to 1 will suppress
% adding space above the next. If a =\morecimdrules= follows,
% we add (positive) =\cmidrulesep= (and again set =\@lastruleclass=
% to one). Otherwise this is the last rule of the current group
% and we can just add =\belowrulesep=. Finally, we close the =\noalign=.
% \changes{v1.618}{2003/03/28}{Change to \cmd{\@xcmidrule}:
%         replace \cmd{\@cmidrulewidth} with \cmd{\@thisrulewidth }}
%    \begin{macrocode}
\def\@xcmidrule{%
   \ifx\@tempa\cmidrule
       \vskip-\@thisrulewidth
       \global\@lastruleclass=\@ne
   \else \ifx\@tempa\morecmidrules
       \vskip \cmidrulesep
       \global\@lastruleclass=\@ne\else
       \vskip \belowrulesep
       \global\@lastruleclass=\z@
   \fi\fi
   \ifnum0=`{\fi}}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\@cmidrulea}
% This code (called below) actually draws the rules. They are drawn
% as boxes in text, rather than in a =\noalign= group, which permits
% the left and right kerning.
%   \changes{v1.6180}{2005/03/16}{add colortbl \cmd{\CT@arc@} command for color support}
%   \changes{v1.618033}{2016/04/27}{add  \cmd{\kern}\cmd{\z@}  after \cmd{\hfill} to protects against unskips}
%    \begin{macrocode}
\def\@cmidrulea{%
   \multispan\@cmidla&\multispan\@cmidlb
   \unskip\hskip\cmrkern@l%
  {\CT@arc@\leaders\hrule \@height\@thisrulewidth\hfill\kern\z@}%
   \hskip\cmrkern@r\cr}%
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\@cmidruleb}
%   \changes{v1.6180}{2005/03/16}{add colortbl \cmd{\CT@arc@} command for color support}
%   \changes{v1.618033}{2016/04/27}{add  \cmd{\kern}\cmd{\z@}  after \cmd{\hfill} to protects against unskips}
%    \begin{macrocode}
\def\@cmidruleb{%
    \multispan\@cmidlb
    \unskip\hskip \cmrkern@l%
   {\CT@arc@\leaders\hrule \@height\@thisrulewidth\hfill\kern\z@}%
    \hskip\cmrkern@r\cr}%
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\morecmidrules}
% This is really a dummy command; all the work is done above
% within the =\cmidrule= routine. We look one step ahead there
% to see if a =\morecmidrules= follows the current =\cmidrule=,
% and if so set the flag. Otherwise,  =\morecmidrules= itself
% does nothing.
%    \begin{macrocode}
\def\morecmidrules{\noalign{\relax}}
%    \end{macrocode}
% \end{macro}
%
%    \begin{macrocode}
%</package>
%    \end{macrocode}
%
% \Finale
%