 The overall account seems to be something like the following: Language requires a coordination of words—or at least sentences—with something signified. Scientific language, Reichenbach claims, requires “coordinative definitions” that specify physical procedures for measurement. A common example is the “definition” of the Paris meter bar as a unit of distance. Definitions in the usual sense occur within a language, but Reichenbach sometimes appears to intend something like an “ostensive” definition (he does not use the term). He gives no account of how such an act can suffice to specify a rule, and he recognizes instances in which it does not, for example that a coordination that measures time by the behavior of clocks does not suffice to provide a rule for deciding relations of time measurements between distant clocks. Various coordinative definitions may thus leave measures of other quantities or relations indeterminate, and these must be specified by some stipulation or other. His chief, but not only, example is the definition of simultaneity (see also Rynasiewicz (2003), and Dieks (2009) for a clear discussion). 