 A state-description for a language L is a class of sentences of L such that, for every atomic sentence \(p\) of L, either \(p\) or \(\neg p\), but not both, is contained in the class. An atomic sentence holds in a state-description R if and only if it belongs to R. A sentence \(\neg A\) (where A need not be atomic) holds in R if and only if A does not hold in R; \((A\wedge B)\) holds in R if and only if both A and B hold in R, and so on for the other connectives in the usual inductive way; \((\forall x)Fx\) holds in R if and only if all the substitution instances of \(Fx\) hold in R. The range of a sentence is the class of state-descriptions in which it holds. Carnap’s notion of validity or L-truth is a maximal notion, i.e., Carnap defines a sentence to be valid or L-true if and only if it holds in all state-descriptions. In later work Carnap adopts models in place of state-descriptions. Models are assignments of values to the primitive non-logical constants of the language. In Carnap’s case predicate constants are the only primitive constants to which the models assign values, since individual constants are given a fixed pre-model interpretation and value assignments to variables are done independently of the models (1963a).