We use the DocFlex/XML XML Schema Documentation Generator to automatically produce hyperlinked documentation of the schema as part of the online documentation at the PreTeXt website, located at
mathbook.pugetsound.edu/doc/schema/. Because this is produced from the XSD version of the schema, it will reproduce the small inaccuracies mentioned above. But it is still a very convenient and informative way to explore the schema, or use it for reference. If you know of a similar tool of the same quality, but which documents RELAX-NG schema, a report would be greatly appreciated.
Do not be intimidated by the list of roughly 300 elements in the left navigation panel. Many are configuration options, many are special-purpose, and many you will never use. (Someday we will do lexical analysis on a substantial range of PreTeXt texts to see just which elements do get used most frequently). Instead, scroll down to the 70 or so “Element Groups”. These are thematic bundles of related elements, named to help you locate them later. The right panel will list the elements near the top as part of the “Complex Content Model.” Just below you will see the “Known Usage Locations” which list places every element in the group may appear. Similarly, if you explore a particular element, you can see the pattern describing the attributes and elements allowed as children, and lists of the possible parents.
The XML Schema Documentation Generator is a commercial program, but provides a free license allowing minimal customization and embeddeding promotion in the output. (Thank-you, Filigris Works!) In particular, as an author you should not need to install or use this program.