Declares a routine interface for use in database definition
    statements. A routine is either a function or a procedure.

    The declared routine acts as a template for calls to the function
    or procedure in DDL statements such as CREATE TABLE, CREATE VIEW
    and CREATE MODULE. The template allows Rdb to validate that
    the routine is correctly named, is passed the correct number
    of parameters and that those parameters are passed compatible
    arguments. For functions the returned data type is used to
    calculate data types for COMPUTED BY, AUTOMATIC and other stored
    value expressions.