This excerpt taken from the PCG 10-K filed Feb 18, 2005.
4.2.3. Excluded Events
The following types of events/Outages shall be excluded from the calculation of the Availability Measures and the Availability Measure Targets:
Scheduled Outages which are scheduled, reviewed and approved by the ISO in accordance with the Transmission Control
Agreement, and
Forced Outages(IMS)which: 1) were caused by events outside the PTO's system including those Outages
which originate in other TO systems, other electric utility systems, or customer equipment, and 2) those Forced Outages(IMS) which can be demonstrated to have been caused by
earthquakes.
Bet you've never seen portfolio analytics like these.