Specifies whether the File Handler checks that all the keys belonging to the indexed file you are opening are defined in your application.
>>-.---.-.----.--KEYCHECK------->< +-/-+ +-NO-+
If you specify KEYCHECK, all key definitions must be specified and must match, otherwise a 3/9 error is returned. If you specify NOKEYCHECK, the File Handler opens the file without any checks on key definitions. If the file is opened with NOKEYCHECK set, and if one or more of the keys does not match, then any I/O operation that explicitly references a non-matching key (for example, a READ or START with the KEY phrase) will result in a 3/9 error.