A start-of-header line is a Texinfo comment that looks like this:
@c %**start of header
Write the start-of-header line on the second line of a Texinfo file.
Follow the start-of-header line with an
@settitle line and,
optionally, with other commands that globally affect the document
formatting, such as
then by an end-of-header line (see End of Header).
The start- and end-of-header lines allow you to format only part of a
Texinfo file for Info or printing. See
The odd string of characters, ‘%**’, is to ensure that no other
comment is accidentally taken for a start-of-header line. You can
change it if you wish by setting the
tex-end-of-header Emacs variables. See Texinfo Mode Printing.