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OPT=IGEN

The remaining OPT= value, OPT=IGEN (Inverse GENeric), has special use. The definition is: Retrieve the entry with the longest key value equal to the supplied key value, but at least one character long. For example, a search key of ABCDE searches as follows:

  1. For ABCDE; if no match is found, the search continues for...
  2. ABCD; if no match, it would then search for...
  3. ABC; and so on through...
  4. AB and...
  5. A

This retrieval option is especially suited for screening messages by message identifier, where generic identifiers (for example, IEF) control all messages that start with that identifier, and less-generic identifiers (degenerating to specifics, such as IEF431I) override the generic identifier in a particular case.

By loading a table with these identifiers, an incoming message identifier can be looked up in one GET OPT=IGEN statement, to find the most-specific match. This avoids looping to examine lists of shorter and shorter identifiers.