This document standardizes terminology and indexes for reporting electric generating unit reliability, availability, and productivity performance measures while recognizing the power industry's needs, including marketplace competition. This standard also includes equations for equivalent demand forced outage rate (EFORd), newly identified outage states, discussion of commercial availability, energy weighted equations for group performance indexes, definitions of outside management control (OMC), pooling methodologies, and time-based calculations for group performance indexes. This standard is intended to aid the electric power industry in reporting and evaluating electric generating unit reliability, availability, and productivity. It was originally developed to overcome difficulties in the interpretation of electric generating unit performance data from various systems and to facilitate comparisons among different systems. The standard also makes possible the exchange of meaningful data among systems in North America and throughout the world. Revision Standard - Superseded. This standard provides a methodology for the interpretation of electric generating unit performance data from various systems and to facilitate comparisons among different systems. It also standardizes terminology and indexes for reporting electric generating unit reliability, availability, and productivity performance measures. This standard is intended to aid the electric power industry in reporting and evaluating electric generating unit reliability, availability, and productivity while recognizing the power industry's needs, including marketplace competition. Included are equations for equivalent demand forced outage rate (EFORd), newly identified outage states, discussion of commercial availability, energy weighted equations for group performance indexes, definitions of outside management control (OMC), pooling methodologies, and time-based calculations for group performance indexes.