Steady state engine performance programs discussed in this Standard will be confined to two basic performance categories: preliminary design or specification. Preliminary design programs may vary in scope, but will be representative of the defined engine performance until the engine is defined by a specification. A specification program will accurately represent the engine described by the specification and will identify the appropriate model specification. Normally, the computer program will be the primary source of performance data. Two additional categories of program are status and data reduction interface programs, which are covered by ARP 1211 and 1210 respectively.