 A more widely advocated approach admitted a conventional element to the use of quantity-terms, while resisting attempts to reduce the meaning of quantity terms to measurement operations. These accounts are classified under the general heading “conventionalism”, though they differ in the particular aspects of measurement they deem conventional and in the degree of arbitrariness they ascribe to such  conventions.[12]  An early precursor of conventionalism was Ernst Mach, who examined the notion of equality among temperature intervals (1896: 52). Mach noted that different types of thermometric fluid expand at different (and nonlinearly related) rates when heated, raising the question: which fluid expands most uniformly with temperature? According to Mach, there is no fact of the matter as to which fluid expands more uniformly, since the very notion of equality among temperature intervals has no determinate application prior to a conventional choice of standard thermometric fluid. Mach coined the term “principle of coordination” for this sort of conventionally chosen principle for the application of a quantity concept. The concepts of uniformity of time and space received similar treatments by Henri Poincaré (1898, 1902: Part 2). Poincaré argued that procedures used to determine equality among durations stem from scientists’ unconscious preference for descriptive simplicity, rather than from any fact about nature. Similarly, scientists’ choice to represent space with either Euclidean or non-Euclidean geometries is not determined by experience but by considerations of convenience.