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