Component interface documentation what do we need and why do we need it?

For at least 4 decades, managers, customers, and anyone else who wanted to acquire software, has bemoaned our inability to specify exactly what is required when we want software built. Those who maintain software or use software complain about the lack of a precise description of what it does. Numerous specification methods, none of which have been found to be satisfactory have been proposed. This paper discusses documentation methods,why we need one and what a good one might be like.