Free Hero Mesh

  expanded during each use. A macro argument token with a single backslash
  expands to the argument in that position, while a macro argument tokens
  with multiple tokens becomes the token with one less backslash. It is
  permitted to redefine existing macros as well as new ones.

{edit <string> <token>}
  Edit a macro. This changes the first token of the definition of the macro
  (which must not be another macro) to the specified token. The token is
  expanded, and must be a single token once it is expanded; that is what it
  will be replaced with. There is a variant with a number in place of a
  string; this will replace the argument of the macro which is currently
  being expanded.

{include <string>}
  Include text from another file into this one. You cannot use {include}
  inside of another macro or in a macro argument. The file must be in the
  current directory, and its name must contain only letters, digits, dot,
  underscore, and minus signs, and must start with a letter or digit. If
  it is a composite puzzle set, then the name must end with ".include",