From an excellent tutorial page, we find that the
\@startsection command is used by all the various
sectioning commands. This command is defined in the
It takes six arguments.
Name of the section command, e.g.,
Depth of the section command, e.g., 0 for part, 1 for
chapter, 2 for section. This value is compared to
tocdepth counters to control numbering of
sections and the depth of the table of contents.
How far the heading should be indented. For no indent,
\z@”, shorthand for zero
If positive, the vertical rubber length to be inserted before the heading.
If negative, the first paragraph after the heading will not be indented, and the absolute value of the length is inserted before the heading.
If positive, the vertical rubber length to insert after the heading.
If negative, use a run-in heading (make it the first part of the first paragraph), and insert its absolute value as horizontal space between the heading and the next word of the paragraph.
Commands that alter the style of the heading.