Although VHDL has “Hardware Description Language” in its name, its behavioral modeling syntax includes logic operators, viz.: and, or, nand, nor, xor, xnor and not, plus other types of operators such as relational, shift, and arithmetic, enabling solution-free behaviour to be specified. VHDL does not require components to be defined; it is capable of black-box behavioural description. Ipso facto, VHDL is a requirements language (but not only a requirements language, it is also a design language). The same is true for many other behavioral modeling languages – they can be used to describe both requirements and design.
Innumerable studies have concluded that requirements problems are the single biggest contributor to cost overruns, schedule slippages and loss of capability in systems […]