The structure that the cleint was reading is the SARGCR record, which is mapped by the CVDEMAC(SARGCR) macro.
Currently, there is no PL/1 structure definition for it.
The key for the SARGCR record is 36 bytes and consists of a GCRID (report name) which is 32 bytes, generation number (2-bytes binary), and sequence number (2-bytes binary).
To do a SARGET EQ for a specific report, those 3 fields would need to be provded, otherwise blank out GCRGEN and GCRSEQ, and do SARGET GE or GT to get first occurrence of the report name provided.
The fields in the GREC.GREC_DATA fields is the SARGCR fields starting with GCRRLEN.
At this time, there is no documentation that details what is returned.