3.1 Generally Sexp-ing

The file format for the configuration items (see Configuration) is composed of comments, structured expressions, and whitespace.

comments

A comment begins with ‘;’ (semicolon) and goes to the end of the line. If you use Emacs, you can add the comment:

          ;; -*- scheme -*-

on the first line to make comments appear differently, presuming syntax highlighting support is enabled.

structured expressions

A structured expression, for the purposes of GNU Alive, is one of:

integer

A decimal¹ number. For instance, 42.

symbol

A contiguous sequence of non-whitespace characters that do not include ‘()’ (parentheses), ‘,’ (comma), ‘'’ (apopostrophe, also known as single-quote), or ‘"’ (double-quote). For instance, www.gnu.org.

That's it!

whitespace

Everything else, that is, all the stuff between comments and structured expressions, is whitespace.