Tutorial :Where can I find help files or documentation for commands like \@startsection for LaTeX?



Question:

I can't find official documentation for the \@startsection command. I already looked in:

  1. LaTeX Wikibook
  2. LaTeX: Structured document for TEX, 2008
  3. beginLatex â€" a book that comes with ProTeX
  4. in the files that comes with MikTeX in the folder doc

and Google. I found a lot of sites that show examples and discussions about it but I'd like to find the official help or document.


Solution:1

The actual command, including its formal definition posted by @JoshLee is contained in the LaTeX 2e source, section 61.2 Sectioning (p 283). It forms part of ltsect.dtx, the bundle containing all sectioning commands for LaTeX. It even includes a pseudo-code interpretation of the actual macro. Here is an extract:

The \@startsection{<name>}{<level>}{<indent>}{<beforeskip>}{<afterskip>}{<style>}*[<altheading>]{<heading>} command is the mother of all the user level sectioning commands. The part after the *, including the * is optional.

  • name: e.g., subsection
  • level: a number, denoting depth of section - e.g., chapter = 0, section = 1, etc.
  • indent: Indentation of heading from left margin
  • beforeskip: Absolute value = skip to leave above the heading. If negative, then paragraph indent of text following heading is suppressed.
  • afterskip: If positive, then skip to leave below heading, else negative of skip to leave to right of run-in heading.
  • style: Commands to set style. Since June 1996 release the last command in this argument may be a command such as \MakeUppercase or \fbox that takes an argument. The section heading will be supplied as the argument to this command. So setting #6 to, say, \bfseries\MakeUppercase would produce bold, uppercase headings.

If * is missing, then increment the counter. If it is present, then there should be no [<altheading>] argument. The command uses the counter secnumdepth. It contains a pointer to the highest section level that is to be numbered.


Solution:2

It’s not a LaTeX command per se (which is why it’s not well documented), but a TeX macro that’s defined in the implementation of LaTeX’s kernel. @Concerned has a good answer, but you can also explore macros in LaTeX’s interactive mode:

~$ latex  **\makeatletter  *\show\@startsection  > \@startsection=macro:  #1#2#3#4#5#6->\if@noskipsec \leavevmode \fi \par \@tempskipa #4\relax  \@afterindenttrue \ifdim \@tempskipa <\z@ \@tempskipa -\@tempskipa \@afterindentfalse \fi  \if@nobreak \everypar {}\else \addpenalty \@secpenalty \addvspace \@tempskipa \fi  \@ifstar {\@ssect {#3}{#4}{#5}{#6}}{\@dblarg {\@sect {#1}{#2}{#3}{#4}{#5}{#6}}}.  


Solution:3

I'd consider the LaTeX companion (second edition) as a very good ressource for this kind of command. It may be not up to date in every aspect, but IMO very much is still valid.


Solution:4

look into the main LaTeX file latex.ltx. You'll find it in the tex/latex/base directory, or let kpsewhich find the place:

kpsewhich latex.ltx  

For my system:

voss@shania:~> kpsewhich latex.ltx  /usr/local/texlive/2011/texmf-dist/tex/latex/base/latex.ltx  

in this file you'll find all definitions.


Solution:5

A lot of LaTex's internals can be mastered only by using the source, but have a look at LaTeX 2e for Class and Package Writers.


Solution:6

See This discussion on the texhax mailing list for where to find the definition in the LaTeX distribution This link (PDF) has some documentation about it.


Note:If u also have question or solution just comment us below or mail us on toontricks1994@gmail.com
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