An RFI is a formal question submitted to clarify unclear or missing details in the project documents, typically answered by the architect or engineer.

Submittals are documents like product data, shop drawings, or material samples sent by the contractor for approval to ensure what's being built matches design intent and specs. 

A change order is a written agreement that modifies the original contract by adding, removing, or revising work, usually initiated by the owner, contractor, or design team.