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Files

It is recommended that logical records relating to the same experimental conditions or 'run' are grouped in one file.

For unlabelled tapes the end-of-file (and end-of-run) is indicated by one EOF mark.

For labelled tapes the end-of-file (and end-of-run) is indicated by an EOF mark and the associated EOF records [5].

End-of-data on the tape (and end-of-file) is indicated by two consecutive EOF marks. It is NOT recommended that files (runs) span from one tape to another.

END-OF-TAPE. It is NOT recommended to write past the EOT reflective marker, therefore, on detection of the EOT marker, the software should backspace over a sufficient number of data records to allow the required end-of-run and EOF records to be written.

RECORD FORMATS. Logical records and physical records, (i.e. physical tape blocks) normally consist of a number of header words, followed by data. In some cases the number of header words in a physical record may be 0.

WORD LENGTHS. All lengths in the physical header are expressed in words where a word is defined as a 16-bit unsigned integer. The logical record wordlength is defined in the physical record header.

byte 0
is defined as the highest order 8-bits of the word,
byte 1
is defined as the next highest order 8-bits, etc.
byte 0
is written to tape before byte 1.


Janne Saarela
Tue May 16 09:44:28 METDST 1995