What are the two parties of referencing called?

Question

If document A references document B, is there a term to describe A’s and B’s role? Maybe we could call B the referent? How about A?

Answer 1

Using terminology from

https://en.wikipedia.org/wiki/Cross-reference#Structure_of_a_cross_reference

I'd say :

A: referencing document (which contains references or cross-references)
B: referenced content (or item, section, etc.)

Answer 2

You're already mostly there with the wording of your question.

Document A is, simply, "the document". Document B is "the reference", or source.