Identifying Archive Files
=========================

Archive files can usually be identified by examining the first few bytes of
the file:

  00 nn cc cc ...      -> Black v1.xx Archive
  00 00 40 FF nn mm lo -> Black v2.xx Archive
  40 00 nn mm lo       -> CJR Archive
  50 4B 03 04 xx xx xx -> ZIP Archive
  ch cc ... 0D         -> GetBack Archive, ch>32, cc=13 OR >32

!word%=first_four_bytes
IF ?word%=0 AND word%?1>0 AND word%?2>33 THEN archive=Black1
IF !word%=&FF400000 THEN archive=Black2
IF !word%=&04034B45 THEN archive=ZIP
IF ?word%=&40 AND word%?1=0 THEN archive=CJR
IF ?word%>32 AND (word%?1>32 OR word?1=13) THEN archive=GetBack