[blueriver]

The question is what kind of documentation.

Most companies that I worked for required a Technical Design Specification for any major software component.

[ComputationalComplexity]

I know, but the problem is that the design spec could be specific or vague based on the company, the clients of most software companies usually do not have too many experienced software engineers(they do it themselves if they had), so most of the design specs turn out to be wordy pieces of bs totally meant for the management.