When `#!key' does not appear in the <extended formals> and there is no <rest formal>, an error is signaled regardless of presence of `#!optional' if there are any remaining actual arguments. But When `#!key' appears in the <extended formals> regardless of presence of <rest formal>, an error is not signaled in spite of superfluous actual arguments. What is its rationale? -- Joo ChurlSoo