Design overview

The input to the message generation program (DFHMGP) consists of the binary number of the message to be produced, the identifier of the component issuing the message, and any information to be inserted in the message. DFHMGP builds the complete message using a prototype held in the message prototype control table, also known as the message generation table (DFHMGT). The message text itself is held not in DFHMGT but in the message domain, from which it is retrieved by the DFHMGPME routine (a component of the DFHMGP load module) when required. DFHMGP finally sends the message to the appropriate terminal.

The prototype statements are invocations of the DFHMGM TYPE=TEXT macro, and are contained in copybooks held in DFHMGT.

The message prototype control table consists of a series of copybooks, DFHMGTnn, each of which contains 1 through 100 messages. They are arranged in such a way that each DFHMGTnn copybook contains prototypes for messages that have identifiers of the form DFHccnnxx, where cc is the 2-character identifier of the component issuing the message, nn is the numerical part of the copybook name, and xx is in the range 00 through 99. For example, the prototype for message DFHAC2214 (belonging to the AC component) is in copybook DFHMGT22.

Within each copybook are invocations of DFHMGM in ascending message number order. All messages sent to the terminal end user have both OPTION=NLS and COMPID specified on their DFHMGM invocations.

The main operands of the DFHMGM TYPE=TEXT macro are:

Other operands are provided on the DFHMGM invocations, but in general these are no longer used.

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