1. A hardware-block timing-constraint specification method, for use at or below an RTL abstraction level, comprising: defining a plurality of hardware-block timing-constraint categories according to at least one of: type of timing constraint; and timing-constraint operating mode; defining a plurality of hardware-block timing-constraint commands; wherein each of the plurality of hardware-block timing-constraint commands is categorized into one of the plurality of hardware-block timing-constraint categories; and encapsulating the plurality of hardware-block timing-constraint commands within a plurality of modules usable, via an application programming interface, in a standalone mode or an integrated mode.