Vague requirement documentation is most often reason of fail in software development projects. One cause of such requirement problems is the language we use when write our documents. Issues and background that are very evident for one person, can be completely new and different for another, so it is creatical to use Elaborative, not Restrictive language in requirement documentation.

An article of Mark Monteleone is a great illustration of how that problem appears and what can be done to avoid it. Must read to all business analyst and other people working with requirements