Gloria omitted during ordinary time

[Gorgias]

ilySHJ:

As far as whether there are instructions or decrees that allow this … the GIRM is the final authority.

Actually, it’s not quite like that. If something actually has authority, then it can supersede the GIRM.

We need to take a look at our terms, here. The GIRM is the General Instruction of the Roman Missal. The Missal, of course, has more precise rubrics. So do the particular Rites (e.g., matrimony).

They work hand-in-hand, not in conflict. The GIRM gives general principles, while the Rites fill in the details.