PL/I programmers should note that I/O areas passed to the Assist module must follow standard IMS™ conventions. That is, the length field for a segment must be defined as a fullword (FIXED BIN(31)). This applies to both input and output data segments; however, the actual segment that is received from and sent to the client uses a halfword (FIXED BIN(15)) length field. Thus, the messages exchanged between the client and server are programming-language independent.