@subsectionand Other Subsub Commands
The fourth and lowest level sectioning commands in Texinfo are the ‘subsub’ commands. They are:
Subsubsections are to subsections as subsections are to sections. (See @subsection.) Subsubsection titles appear in the table of contents.
Unnumbered subsubsection titles appear in the table of contents, but lack numbers. Otherwise, unnumbered subsubsections are the same as subsubsections.
Conventionally, appendix commands are used only for appendices and are lettered and numbered appropriately. They also appear in the table of contents.
@subsubheading command may be used anywhere that you want
a small heading that will not appear in the table of contents.
As with subsections,
@appendixsubsubsec do not need to be used in ordinary
@subsubsection may also be used within
In Info, ‘subsub’ titles are underlined with periods. For example,
@subsubsection This is a subsubsection
188.8.131.52 This is a subsubsection ...............................
The TeX, HTML, Docbook, and XML output is all analogous to the chapter-level output, just “three levels down”; see @chapter.