C.2.3:1 - Problem frame

Transdisciplinary work needs one shared way to speak about rigor of expression. A research hypothesis in constrained natural language, a software interface specification with explicit invariants, a controller model checked against hybrid obligations, and a proof-bearing formal development are not comparable by domain lore alone. They are comparable by how strictly the content is expressed.

Historically, that distinction drifts. Teams mix editorial maturity, organizational status, notation choice, proof support, and scope narrowness into one vague story about something being more formal. C.2.3 removes that drift by giving FPF one explicit U.Characteristic for rigor of expression.