Record Definition Language › RDL Field Type Descriptions › Field Type GA—Garbage Data (Permanently Unused Fields)

Field Type GA—Garbage Data (Permanently Unused Fields)

Field type GA is specified when the content of a field is no longer of value in the file. This type can be specified for permanently unused fields, fillers, alignment bytes, and so on. They are deleted in the compressed record, but appear as binary zeros upon re-expansion. If these fields were not originally zeros, the expanded record is not an exact replica of the original. Checking used by CA Compress does not consider type GA fields.

Consider variable-length input records, where the 2 low-order bytes of the IBM standard Record Descriptor Word (RDW) are always binary zeros. Those 2 bytes can conveniently be specified as GAF2.

All 4 bytes of the RDW are sometimes superfluous in defining variable-length records, because the length may be implicit in the record content. The RDW may then be defined as GAF4. The Expansion Utility fills in the length automatically. The EXPAND subroutine supplies the length if the output record address (first parameter) and the record length address (third parameter) are the same.