188.8.131.52 Item Definition
Item definition includes performance requirements and hardware
concept to the extent known at the time the model and prediction are prepared.
Characteristics of the item are stated in terms of range, altitude, speed,
maneuverability, environmental conditions, power, or such other parameters as
may be applicable. The manner in which the item and its subdivision operate is
usually expressed by means of functional diagrams which become the basis for
the reliability block diagrams. Normally, the initial item definition used for
the feasibility prediction will be lacking several details and will require
certain assumptions as to environmental conditions, design configuration, etc.
The item definition is defined and updated as more information becomes
available to support the preliminary design prediction, and subsequently, the
detailed design prediction. As the item description is progressively updated,
higher levels of accuracy will be attained for prediction