There are as many "documentation schemes" as there are companies - everybody wants it done "the way *they* learnt" or "the way it's done in XYZ", and we often tend to end up with a mixture of documents with crossover functionality and often contradictory information.

I recently completed a job for a large UK PFI company, who attempt to follow civil service documentation standards, (including couriering 'sensitive' design docs because they hadn't learn about encrypted mail...) along with a few wrinkles of their own. It was a nightmare. 5 different documentation departments, each with their own set of standards. Requirements passed to Functionality who passed to Low-level Design who passed to Interface Design...

It left me thinking that most projects need just two documents - a specification, and a user manual - "What we want" and "How we did it". (At a pinch, just the specification, which in theory could serve as the manual too, once translated into User {g}). A requirements document can be quite happily signed off, then sent to the design department. They can turn this into a completely unrealistic set of achievables, simply from their choice of implementation menthod - one, which furthermore, can completely contradict the document coming in from the hardware guys. Your implementation could follow both the requirements spec and the hardware spec, but fail the design requirements. You know the old cartoon with the rope swing?...

If however, you're lucky enough to get all your people round a table at the same time, and hack out a single document, then you've got your Bible. This would include a test plan, and an implementation everbody was happy with - I've seen a project take an extra month simply because the database design doc. wasn't part of the initial process, and 3 months in, they decided to impose their own standards.Timescales can be thrashed out, you can follow it to the letter, and get paid accordingly. With a comprehensive single signed-off document, you know when the job's a good 'un, and you're finished. All the boxes in the spec are ticked.

Good luck with the deadlines,
Ben.