This chapter gives the scoping rules for Theta. It also describes variable declarations and equates, two important constructs that introduce scoped identifiers.
When we say that an identifier is scoped, or that it has a scope, we mean it is defined within a particular scope. The scoping rules given below (4.4) ensure that a given identifier is either not defined within a scope or is defined exactly once, and that external names (4.3) are never confused with scoped identifiers within a program unit (1.7).