The handler tag must appear in every .srf file, including .srf files included in other .srf files.
The handler tag must precede all other non-comment tags, and must appear within the first 4096 characters of the file. (Note that BIS/IIS
allows include tags to precede the handler tag.)
Only one handler tag in each .srf file is permitted. On BIS/Apache, multiple handler tags are allowed, but only the first encountered in the file is relevant.