Human capital is substitutable, but not transferable like land, labor, or fixed capital. Ordinarily, coreferring names are substitutable "salva veritate", that is, without change in truth value. Rate transparency had elevated the importance of incorporating market positioning against substitutable alternatives. Both of these industries have highly specialized labor conditions and are generally not substitutable. Its behavior is defined in terms of "provided" and "required" interfaces, is self-contained, and substitutable. In this theory, financial instruments of different terms are not substitutable.