I've just scored a gig to review and refresh some established (software) user documentation, including streamlining the processes by which updates are managed and applied, so I've recently been researching the whole area to update my knowledge.
DTP - There's still some debate about which products are the most suitable, and as you might expect, some writers have entrenched positions on the matter. Those who have been doing it for years swear by products like FrameMaker, which is still a popular option. The argument for products of this type is that they are true DTP solutions built for managing text and illustrations in bulk, and although they are harder to learn initially, they unquestionably deliver the required functionality. The downside in a collaborative environment is that the tech writer may be the only one who has it on his machine and knows it, so it results in a bit of double handling etc.
The argument against Word used to be that it is only a Word Processor with aspirations, and that it is not so good at manipulating a mixture of images and text. Also, older versions on less powerful PC's were very poor at handling large documents, as manuals often tend to be. Those arguments appear to have largely evaporated with newer versions of Word and the availability of beefy processors with plenty of memory.
My take is that Word is now a perfectly acceptable alternative, and the fact that almost everyone has it (or can at least handle a .doc document with an alternative) adds to its appeal where text needs to be gathered from multiple sources. Most companies output to pdf for the finished product for easy download and guaranteed format/printability.
ONLINE HELP - This is very much the name of the game these days for software related documentation. But there is still a (usually mandatory) requirement for hard copy, so the ideal situation is where the two can be developed and maintained side by side. Some products have emerged that are called 'single source' in that their aim is to capture once and publish to many alternative formats. Most will accept input directly from word and publish in doc, pdf, winhelp, html help and xml formats etc. I will probably be investigating some of these alternatives in the coming weeks. The market leader seems to be WebWorks Publisher for Word (
www.webworks.com).
USER MANUAL - The key to the success or otherwise of all documentation is that it should be pitched appropriately to the class of user it targets. One of the commonest complaints about user documentation is that it does not address the needs of the 'dumb' user. A lot of documentation is prepared by technical SME's, often the people that develop the product, then refined by somebody who is one step removed from the front line but still technically oriented. The critical final step (unlikely to be argued about by anyone on this board!) of having it reviewed and polished up by a technical writer with a dumb third party user perspective is often omitted.
Every product will have different requirements of course, but in general it's accepted that most users are not concerned with 'how' something works, only how they can use it with the minimum of fuss. This generally implies including a number of worked examples and illustrations to guide them without making any assumptions about how much they know.
Ideally, documentation of complex products should come in three flavours - complete rookie, intermediate and expert. But that is usually impracticable, so the compromise version usually fails the rookie while patronising the expert and not giving him enough detail for his purposes. Most s/w products, however, usually come with both a user's guide and a system administrator's guide, so that addresses the problem to some extent.
KNOWLEDGE BASE/USER GUIDE - Not sure exactly what you mean here, but I do have a view about how knowledge bases and online user guides can interact. The availability these days of the HTML/web hypertext environment means that basic online help can be augmented tremendously by hyperlinks that connect the user to relevant deeper information, troubleshooting tips, reported problems and the like. If one could make the assumption that every possible user was connected to the internet, online help could be linked to the originating company's public web site and automatically have up-to-date knowledge base info available. As it is, while we're close to that nirvana it's probably not a safe assumption, so an alternative would be to make a set of downloadable html-based support files available for users to access on their local network, which could be refreshed periodically.
Hope this helps.
