\ That's a comment; it ends at the end of the line ( Another comment; it ends here: ) .s
\ and ( are ordinary Forth words and therefore have to be
separated with white space from the following text.
\This gives an "Undefined word" error
The first ) ends a comment started with (, so you cannot
nest (-comments; and you cannot comment out text containing a
) with ( ... )4.
I use \-comments for descriptive text and for commenting out code
of one or more line; I use (-comments for describing the stack
effect, the stack contents, or for commenting out sub-line pieces of
code.
The Emacs mode gforth.el (see Emacs and Gforth) supports
these uses by commenting out a region with C-x \, uncommenting a
region with C-u C-x \, and filling a \-commented region
with M-q.
Reference: Comments.