# Where can I find an online manual for low-level LaTeX commands?

Is there an online manual for low-level LaTeX commands I can download?

I am looking for something which would have, for example:

\newif\ifportrait
\newif\ifcustomsize
\newif\ifdebug

\makeatletter
\renewenvironment{theindex}
{\if@twocolumn
\@restonecolfalse
\else
\@restonecoltrue
\fi
\setlength{\columnseprule}{0pt}
\setlength{\columnsep}{35pt}
\begin{multicols}{3}[\section*{\indexname}]
\markboth{\MakeUppercase\indexname}%
{\MakeUppercase\indexname}%
\thispagestyle{plain}
\setlength{\parindent}{0pt}
\setlength{\parskip}{0pt plus 0.3pt}
\relax
\let\item\@idxitem}%
{\end{multicols}\if@restonecol\onecolumn\else\clearpage\fi}
\makeatother

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With "online manual" you mean "manual I can download online" or "manual which pops up by itself when an error appears"? Do you mean low-level LaTeX commands or plainTeX macros and primitives? –  Martin Scharrer Jul 12 '11 at 15:48
–  Martin Scharrer Jul 12 '11 at 15:50
low-level LaTeX, not plainTeX. –  Regis da Silva Jul 12 '11 at 16:06

The LaTeX2e kernel macros are documented in source2e. An unfinished macros2e document lists all of its macros which are deemed directly useful for package authors.

If you need help with the underlying plainTeX macros and primitives (which lie even deeper than the LaTeX kernel) then I suggest the free books TeX for the impatient and TeX by Topic which are freely available on CTAN.

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IOW texdoc source2e, texdoc impatient. I would also add texdoc texbytopic. –  przemoc Jul 12 '11 at 15:59
@przemoc: Thanks for mentioning it. I don't like to constantly repeat that it can also be accessed by texdoc. If it is on CTAN then it should be also accessible that way, but some people might not know texdoc. –  Martin Scharrer Jul 12 '11 at 16:01
@Regis: I was studying source2e and the latex.ltx file. –  Martin Scharrer Jul 12 '11 at 16:06
Calling a 400 page manual “for the impatient” is a rather strange definition of “impatient”. –  Caramdir Jul 12 '11 at 16:12
@przemoc: Compared to that, lshort really does seem short. –  You Jul 12 '11 at 22:38