Query Reply Data Structures Supported by EHLLAPI

This appendix lists and defines the query reply structures supported by the EHLLAPI structured field interface for PC/3270. Refer to IBM 3270 Information Display System Data Stream Programmer's Reference or, in the case of an IBM licensed program, the documentation for the specific licensed program.
  1. EHLLAPI must scan the query reply buffers to locate the destination/origin ID (DOID) self-defining parameter (SDP) for the structured field support to work and be reliable. The DOID field is then filled in with the assigned ID.
  2. The application should build the query reply data structures in the application's private memory.
  3. Only cursory checking is performed on the query reply data. Only the ID and the length of the structure are checked for validity.
  4. The 2-byte length field at the beginning of each query reply is not byte reversed.
  5. Only one distributed data management (DDM) base-type connection is allowed per host session. If the DDM connection supports the SDP for the DOID, multiple connections are allowed.
  6. If a nonzero return code is received indicating that an application is already connected to the selected session (RC 32 or 39), use that presentation space with caution. Conflicts with File Transfer, and other EHLLAPI applications might result.