No documentation on the 'tags' feature

I am currently trying to review https://github.com/minetest-mods/drawers/pull/102 but at the time of writing, there is simply a TODO about 'tags' on https://github.com/mt-mods/pipeworks/wiki . Surely, code may does answer some questions - but it also paves the way to relying on (potentially) unsupported or unintended behaviour.

Questions that the documentation should answer:

1. What is the goal of that feature?
2. How do you set it up? Which nodes can make use of it?
3. What are the relevant API functions?
4. Is there only msg.tag or also msg.tags? If there's both - which does take precedence?
5. What are the expected data formats of those functions?

Thank you.

EDIT: A rough documentation exists in https://github.com/mt-mods/pipeworks/pull/107#issuecomment-1925943467 - but that's not where a modder should (or rather would) look for it.

Start with the TODO on the Pipeworks wiki and the rough documentation in the comment on pull request #107. Verify that the documentation answers the five listed questions, including setup, supported nodes, API functions, tag precedence, and data formats. Done means the information is available where modders would normally look rather than only in a pull-request comment.