Sectioning commands provide the means to structure your text into
units. The document style determines which
sectioning commands are supported. They should be used with the
following heirarchy:
\part
\chapter (report style only)
\section
\subsection
\subsubsection
\paragraph
\subparagraph
\subsubparagraph (milstd and book-form styles only)
\subsubsubparagraph (milstd and book-form styles only)
The counter for each level is reset when the
level above is incremented (except chapters are numbered sequentially
regardless of the part).
All sectioning commands take the same general form:
\chapter[optional]{title}\label{lab}% optional, for cross referencing
text for this unit ...
...
In addition to providing the heading in the text, the mandatory
argument of the sectioning command can appear in two other places:
the table of contents
the running head at the top of the page
You may not want the same thing to appear in these other two places as
appears in the text heading. To handle this situation, the sectioning
commands have an optional argument that provides the text for these
other two purposes.
The title or optional title are moving arguments so
fragile commands contained in these
arguments must be protected.
All the sectioning commands have *-forms that print a title, but do not
print a number with the title and do not incement the relevant
counter and do not make an entry in the
table of contents.
A blank line before or after a sectioning command has no effect.