A formal question raised by one project party to another, usually the contractor asking the design team to clarify or resolve a gap in the drawings or model. RFIs are the standard mechanism for resolving ambiguity during construction - when something on site doesn't match the documents, or two disciplines' information conflicts, an RFI captures the question, routes it to whoever can answer, and creates a written record of the resolution. Frequent RFIs on a project are often a sign of coordination problems that better BIM clash detection could have caught earlier.