There is one resource data (RED) record for each defined resource in the system. RMF™ maintains and updates all fields in this record as needed. RMF uses RED records to access USE/WAIT records (in the case of the Monitor III data gatherer) or user records (in the case of a data gathering user exit routine). RED records are fixed in length, and contain X‘3F’ in the resource identifier (REDREDID) field when RMF invokes your data gatherer user exit routine. RMF uses this identifier to locate your user records, which also must have the same hexadecimal identifier. The RED record also contains the offset to the first user record (REDFUWDO), the length of your user exit records (REDUSERL), and the number of user exit records (REDUSERN) created during a CYCLE. While RMF maintains all the fields in the RED record, it obtains the length and number of user records from values you provide in the interface area used by the Monitor III data gatherer and your user routine. When RMF invokes your user exit, the second input parameter points to this interface area (see Programming a data gatherer).