Functional Baseline

The complete set of functions (and their associated measures) necessary for a system to meet its intended Operational Requirements in the context of a preliminary design, formally designated as the initial technical baseline for subsequent development.

In this context, “complete” is used prescriptively rather than restrictively. When complete, a hardware design will always have functions in addition to those specified in the Functional Baseline, simply as a consequence of the design (see also feature)1. The baseline specifies the minimum set acceptable, not the total set. This point is often missed by modern System Engineers.

The cost-effectiveness and utility of the extra functions can end up being significant discriminators in future procurements. It is, however, important that they don’t accidentally become “requirements”; it is also important that we control their propagation into other parts of the system, in order to avoid unintended consequences. 

Footnotes
  1. This is far less true of software design, which exists only in the abstract.[]