There is extremely confusing terminology in the Cite codebase, notably:
- The term "key" is used for a multitude of entirely different concepts. There are even comments left where "key" is used to describe the ability of naming <ref> with the name="…" attribute. This is also why messages like cite_error_ref_too_many_keys contain the word "key". See T299280#9384546 for the full explanation.
- What is an "id"?
- What qualifies as an "index" and what doesn't?
- What does it mean for a reference to have a "number"? There are several numeric values assigned to each reference.