Updating system specification
Don't create a fifty-page document when a five page one will do.
It is important to understand that I am not saying that a larger document is automatically of lower quality than a shorter one, but I am saying that it is likely to be perceived as such until proven otherwise.This is an example of the practice Single Source Information.As you see in Figure 1, the agile strategy is to defer the creation of all documents as late as possible, creating them just before you need them via a practice called "document late".Ideally, an agile document is just barely good enough, or just barely sufficient, for the situation at hand.Documentation is an important part of agile software development projects, but unlike traditionalists who often see documentation as a risk reduction strategy, agilists typically see documentation as a strategy which increases overall project risk and therefore strive to be as efficient as possible when it comes to documentation.These notes may be nothing more than point-form information as there is no need to "polish" documents until just before final delivery of them. Documentation throughout the software development lifecycle. By waiting to document information once it has stabilized you reduce both the cost and the risk associated with documentation.
Cost is reduced because you won't waste time documenting information that changes, which in turn motivates you to update the documentation.
The large document would very likely have most of the information that you need to maintain and enhance your system, but would you trust the information contained in it?
The shorter document very likely wouldn't contain the detailed information you need but it would provide a map from where you could dive into the source code, or other documents, for details.
You should strive to travel as light as you possibly can, writing on just enough documentation for the situation at hand which is just barely good enough to fulfill it's purpose.
One way to achieve this is to build larger documents from smaller ones.
Agilists write documentation when that's the best way to achieve the relevant goals, but there often proves to be better ways to achieve those goals than writing static documentation.