Thanks, I've been curious about this spec for a while and had little luck turning up a concise description of the format. One question, if I want to write multiple consecutive EOFs (I'm thinking of classic HP3000 MPE :STORE format tapes here) do I write two zero-length records for each, or do I "compress out" the zero-length records in the middle? Say I want to write two EOFs, do I write {0,0,0,0}, {0,0,0,0}, {0,0,0,0}, {0,0,0,0} or {0,0,0,0}, {0,0,0,0}, {0,0,0,0}? I'm hoping it's the former.