Vijay Kumar Bagavath Singh wrote: Documentation is seldom static and always in a state of flux. I think most buyers of books are either students or those who are fairly new to the application. Though internal implementation of an an application may change, the basic user commands remain more or less stable. The focus should be on these core commands, which give life to the application. If the books provide material which can give a firm grounding on the broad principles behind applications, with concrete examples based on a reasonably current and stable distribution of the application, the user can adapt to the changes without difficulty.