This document is a guideline on how to write DocBook documents using the tools group's document authoring work-flow, and at the same time make them validate and compile, and comply with the Atmel style guide.
The Atmel style may change. This implementation of the style may change. If you are reading an old copy of this document, it may not be accurate anymore. So if you see differences between your document and this style guide, you should probably fetch a newer copy of the style guide.
It is also a good idea to read this document both as a PDF and as a HTML document. That way, you will see how the examples render in both PDF and HTML.
Except from that, you should not worry too much about the style. Let the system do the formatting for you.
This document will not teach you DocBook. You should find an online guide or book.
Neither will it say anything about structure nor disposition. For guidelines on User Guide structure, see ???.