Invisible comments

@z...@x

If a source or include file begins with @z (in the very first two characters of the file), then all material is skipped until and including a line beginning in column 1 with @x [except that lines of the form $Keyword: text of keyword $ are processed; see $KEYWORD, ATK_ (source files), or ATk (include files)].

@%

All material until and including the next newline is completely ignored.

@%%

As @%, but also skip blank lines that immediately follow the current line.

For example,

     @z
     Author:  J. A. Krommes
     @x
     @c @% This sets the global language to C.
     @* EXAMPLE.