XEFORd is the equivalent forced outage rate demand without outside management control (OMC) events.  It is a measure of the probability that a generator will not be available due to forced events when there is demand for the generator. 
More information on UCAP can be found in the Resource Adequacy Business Practices Manual (BPM-011) Appendix H, and in the North American Electric Reliability Corporation (NERC) Data Reporting Instructions.