Guidelines are just that. They are nothing more and nothing less. If these guidelines are overridden a reason should be present, and be documented or commented, if it is feasible.
For (programming) languages and document formats prefer using the most official or the most common guidelines, if there are no guidelines of this project applying to the aspect in question. In other words, language and documentation specific guidelines of this project try to only override public guidelines instead of writing complete custom guidelines from scratch.
The project structure, its contents and products has to represent a discovery based network of perspectives and changes. The project and its parts should be portable, extendable, adaptable, deletable and comply with Perspective's guidelines .
This specifically means, that the file and content path of a particular information (for an XML element, this would be the file path + the XPath pointing to the XML element) should identify and describe or at least summarize the content's meaning. This also means, that in an ideal case, one should be able to guess, where to look, for a particular content without knowing where the files are located