A7.8 Magnetic Tape Label Specifications

NOTE: The BAM, GLG, HED, KEP, LAN and SIM experiments have requested that no magnetic labels be written onto their EDR tapes. For these experiments, the following specifications will not apply. Instead, their non-labeled EDR tapes will begin with the first data record and end with two consecutive end-of-file (EOF) marks.

A7.8.1 Structure and Organization Overview

Each individual experiment EDR tape shall consist of an IBM magnetic label consisting of a Standard Volume Label (VOL1) and two Standard Data Set Labels (HDR1 and HDR2) followed by a tape mark. Following the tape label is the data file containing instrument science records. At the end of the data file there shall be a tape mark followed by a trailer label. The trailer label shall be followed by a single tape mark if data is to follow onto an additional reel of tape or a double tape mark if this is the last tape produced. Refer to Figure A7-6 for an EDR data tape recorded on multiple tape volumes. It is not expected that any ULS EDR products will require multiple tape volumes.

Figure A7-6 EDR File Structure

A7.8.2 Magnetic Label Substructure Definition

The magnetic label consists of three physical records which are:

1) the standard volume label (VOL1),
2) the standard data set label (HDR1), and
3) a second standard data set label (HDR2).

VOL1 Definition

The VOL1 record contains 80 EBCDIC characters for a total of 20 32-bit words. The VOL1 record gives information on the tape number according to Table A7-7.

Table A7-7 VOL1 label contents

HDR1 Definition

The HDR1 record contains 80 EBCDIC characters for a total of 20 32-bit words. The HDR1 record gives information on data set name, tape number of first volume in series of volume(s), tape creation date, and block count according to Table A7-8.

Table A7-8 HDR1, EOV1, EOF1 label contents

HDR2 Definition

The HDR2 record contains 80 EBCDIC characters for a total of 20 32-bit words. The HDR2 record gives record format, block length, record length, tape density, and related information according to Table A7-9.

Table A7-9 HDR2, EOV2, EOF2 label contents

A7.8.3 Science Data File Definition

The science data file consists of experiment data as well as spacecraft engineering and spin phase. These records shall each contain a standard SFDU header and a data block. The header is described in Sections A7.1 and A7.2 while the data block formats are described in Sections A7.3 and A7.4.

A7.8.4 Trailer Label Definition

The trailer label consists of either

1) a pair of end of volume labels (EOV1 and EOV2) or
2) a pair of end of file labels (EOF1 and EOF2).

The EOV1 and EOV2 labels are used in the case where a data set cannot be completed on the current tape and must continue on an additional reel of tape; the EOF1 and EOF2 are used in the case where a data set completes on the current tape, whether the first tape or nth tape created. The formats of EOV1 and EOF1 are indicated in Table A7-8; the formats of EOV2 and EOF2 are indicated in Table A7-9.

Next: A7.9 Physical Tape Label Specifications