If you wish to recommend content or updates for the official book, visit the website at http://www.slackbook.org/, verify the current state of the book and follow the directions to contribute.
Slackware Linux may be one of the oldest surviving Linux distributions but it's still regularly updated and includes the latest releases of many of the most popular free software programs. While Slackware does aim to maintain its traditional UNIX roots and values, there is no escaping “progress”. Subsystems change, window managers come and go and new ways are devised to manage the complexities of a modern operating system. While we do resist change for change's sake, it's inevitable that as things evolve documentation becomes stale — books are no exception.