When Distributed FileManager/MVS detects a problem with the input DDM data stream, a "syntax error" (SYNTAXRM), "protocol error" (PRCCNVRM), or "error communications message" (ERRCMNMSG) reply message is built by the reply message builder. Additionally, for SYNTAXRM and PRCCNVRM, the reply message builder writes a record to the system LOGREC file. The LOGREC record includes return and reason codes that identify the subcomponent/module that detected the error. The entire reply message and its SRVDGN is included in the LOGREC record.
A DDM data stream error is categorized as a "source system error." For a discussion of Distributed FileManager/MVS diagnostic techniques that examine DDM data stream errors on the MVS system, see Slip trapping for a specific reply message, "GTF Tracing of Input/Output Buffers," and Formatting LOGREC records. However, because the DDM data stream is not necessarily generated by the end user on the source system, some intervening software or hardware product could have generated the error. (Note: If this type of error is discovered, diagnostic techniques outside of Distributed FileManager/MVS might be required.)