The fourth and lowest level sectioning commands in Texinfo are the `subsub' commands. They are:
@subsectionCommand.) In a printed manual, subsubsection titles appear in the table of contents and are numbered four levels deep.
@subsubheadingcommand may be used anywhere that you need a small heading that will not appear in the table of contents. In Info, subsubheadings look exactly like ordinary subsubsection headings.
In Info, `subsub' titles are underlined with periods. For example,
@subsubsection This is a subsubsection
This is a subsubsection .......................
Go to the first, previous, next, last section, table of contents.