 On Goodman’s broad, structuralist way of thinking, representational systems in general consist of sets of possible physical objects that count as token representations. Objects are grouped under syntactic and semantic types, and interesting differences between kinds of representational system track differences in the way syntactic and semantic types relate to one another. Digital systems are distinguished by being differentiated as opposed to dense. The condition of syntactic differentiation is met when the differences between classes of token representations are limited such that it is possible for users of the system always to tell that a token belongs to at most one class. The condition of semantic differentiation is met when the extension of each type, or the class of referents corresponding to a class of token representations, differs in limited ways from the extension of any other type; so that users of the system can always tell that a referent belongs to at most one extension. Goodman provides the following example of a simple digital computer, a system that meets the conditions of both syntactic and semantic differentiation: Say we have an instrument reporting on the number of dimes dropped into a toy bank with a capacity for holding 50 dimes, where the count is reported by an Arabic numeral on a small display (Goodman 1976: 159). In this system, the syntactic types are just the numbers 0–50, which have as their instances the discrete displays, at different times, of the corresponding Arabic numerals. Both conditions of syntactic and semantic differentiation are met because the relevant differences between instances of different numbers are both highly circumscribed and conspicuous. This means that users of the system can be expected to be able to read the display, or determine which number is instantiated on the display (syntactic differentiation) and which numerical value, or how many coins, is thereby being indicated (semantic differentiation).