The Three Operational Relativities Fixed‑C, Fixed‑T, Fixed‑L

This note shows how one can formulate three equivalent operational versions of relativityby keeping fixed, at will, just one of the three fundamental quantities—speed limit C, time T,or length L. A simple GPS test demonstrates that all three conventions yield identicalexperimental predictions. Hence, space-time curvature in General Relativity is amathematical construction tied to the choice of holding C constant, not an unavoidablephysical substance.