Purpose encompasses both the purpose of your tag set and the specific uses envisioned for your documentation.

Purpose of tagset — For example, the purpose of the JATS Publishing Tag Set (Blue) is to provide a standardized format for users to regularize and optimize journal article data for exchange with publishing, hosting, or archiving partners. The JATS model works as a conversion target for article content provided both in XML and non-XML formats. The purpose of the JATS Archiving and Interchange Tag Set (Green) is to provide a standardized format in which to preserve the intellectual content of previously-published journal articles, capture structural and semantic components, and provide a single format into which content from many providers can be translated easily, with minimal loss.

Both of these are descriptive not a prescriptive missions, therefore, JATS is an enabling tag set, it does not enforce!

Purpose of documentation — Documentation also has a purpose, which should be decided before work begins. The primary purpose of tag set documentation might be:

The worst purpose is the last: one omnibus documentation set to rule them all. JATS Tag Libraries are mostly intended for reference, but contain some tutorial aspects.