 According to Kulvicki, the semantic features of a picture are the “features the picture depicts its scene as having”, while its syntactic features are the colour and shape properties that are “relevant to the semantics of the picture” (2014: 92–93). Not all of a picture’s colour and shape properties qualify as syntactic features. For example, the brownish colour of a sepia photograph is merely an “incidental” feature. Kulvicki argues that a pictorial symbol system has four characteristics: (a) repleteness, i.e., a relatively wide range of properties of a picture qualify as syntactic features, e.g., colour, thickness of lines, etc.; (b) sensitivity, i.e., small changes to a picture in respect of any of these properties are syntactically significant (cf. Bach 1970: 128–132); (c) richness, i.e., “there are at least as many possible denotations in the system as there are syntactic types” (Kulvicki 2006: 38); (d) transparency, i.e., if part of a picture X depicts a picture Y, then that part of X has the syntactic features that Y is depicted as having.