@chapter@chapter identifies a chapter in the document.  Write the
command at the beginning of a line and follow it on the same line by
the title of the chapter.
  
For example, this chapter in this manual is entitled "Chapter
Structuring"; the @chapter line looks like this:
     @chapter Chapter Structuring
     
  In TeX, the @chapter command creates a chapter in the
document, specifying the chapter title.  The chapter is numbered
automatically.
  
In Info, the @chapter command causes the title to appear on a
line by itself, with a line of asterisks inserted underneath.  Thus,
in Info, the above example produces the following output:
     Chapter Structuring
     *******************
     
  Texinfo also provides a command @centerchap, which is analogous
to @unnumbered, but centers its argument in the printed output. 
This kind of stylistic choice is not usually offered by Texinfo.