2.5.2 Interfaces

An interface has the form:

    INTERFACE id;
      Imports;
      Decls
    END id.

where id is an identifier that names the interface, Imports is a sequence of import statements, and Decls is a sequence of declarations that contains no procedure bodies or non-constant variable initializations. The names declared in Decls and the visible imported names must be distinct. It is a static error for two or more interfaces to form an import cycle.