FOR RECIPIENTS OF ANSI LABELED TAPES:


ANSI labeled tapes are provided to KERMIT requestors who:

  (a) asked for them (usually VAX/VMS, RSX-11, or RSTS/E sites);
  (b) didn't mention tape format specifically, but have VAX/VMS;
  (c) asked for a tape in a format we cannot provide; or
  (d) did not specify a system or tape format.

All systems are supposed to be able to read ANSI labeled tapes, which,
according to ANSI standard X3.27-1978: "Magnetic Tape Labels and File
Structure for Information Exchange", should be the universal medium
for exchange between mainframe computers.  The tape is written on a
DECSYSTEM-20 computer, whose implementations of the ANSI standard is
described in "TOPS-20 Tape Processing Manual", Digital Equipment
Corporation AA-H180A-TM, January 1980.  

The tape is written as follows:

Tracks:   9
Density:  1600 bits per inch
Parity:   Odd

Character Encoding:  ASCII (ANSI X3.4-1968)

ANSI labels (each label is an 80-byte record, encoded in ASCII):
Each label begins with a 4-character identifier, like VOL1, HDR1, EOV1, etc.
  Volume label  (VOL1): Volume name is KERMIT, in character positions 5-10.
    The volume label appears only at the beginning of the tape.
  File Header 1 (HDR1): File name is in character positions 5-21.
  File Header 2 (HDR2): Record Format (F, D, or S) in 5 (it's always "D"),
                        Block length in 6-10,
                        Record length in 11-15.
  After HDR1 and HDR2 comes a single tape mark (tm) then the contents of the
  file, terminated by another tm.  The (HDR1, HDR2, tm, file data, tm) sequence
  is repeated for each file.  At the end of file, there may be EOF1 and EOF2
  labels; if present, they may be skipped.

  At the end of tape will be EOV1 and EOV2 labels to indicate end of volume,
  followed by a double tape mark.

Record Format: "D" -- variable length records with a 4-digit ASCII length field
  at the beginning of each record (the length includes the length field
  itself), line terminators stripped, and no record crossing a block boundary.
  "F" (fixed length record) format, although simpler to read, was not used
  because the KERMIT distribution would not fit on a standard 2400' reel of
  tape because of space wasted by padding each record with blanks.

Record Length:  Variable, maximum 300 (no lines of text or program source in
  the Kermit distribution are more than 300 characters long; very few are
  longer than 300).

Block Length:  2000

Only printable files (text, program source, text formatter source, or hex) are
included on this tape.

[End of <KERMIT>ANSITAPE.DOC]