Equated identifiers are introduced by equates (4.6), type specifications (9.2), routine implementations (10.2), method implementations (10.4), formal parameter declarations (9.3), classes (10.4), and superclass declarations (10.5). Variables are introduced by declarations (4.5), instance variable declarations (10.4), formal argument declarations (10.2), and special declaration forms in the tagcase (8.11) and typecase statements (8.12).
An equated identifier has a scope that is the entire scoping unit containing the construct that introduces it, while a variable has a scope from its declaration to the end of the containing scoping unit.