A taxonomic wheel, useful for representing the capabilities of scripts.  The four quadrants of the wheel represent the four major kinds of linguistic information that writing systems typically transmit.  The radical axis runs from theoretically complete information at the centre to zero information at the edge.  There is no known human script that delivers complete information, but *every* known script gives *more than one kind* of information, bracketing completeness in some degree.  As a consequence, no known script in actual use can be correctly represented by only a single point on the wheel.

Robert Bringhurst, The Solid Form of Language: An Essay on Writing and Meaning