RE: region face has no background by default for new frames?

[Drew Adams]

        Eval these: (face-background 'region) ==> "lightgoldenrod2"
                (face-background 'region t) ==> nil
    
        The latter seems wrong to me. If I read the doc string of
        `face-background' correctly, this would be saying that "the default
        [background] for face region (for new frames)" is nil. And that
        doesn't seem correct.
    
    I think that the "default for new frames" does not include what is
    specified in the defface.  It is what you set by calling
    set-face-background and specifying t for the frame.  That overrides
    what the defface says; but usually it isn't specified nowadays.
    
    I tried to clarify the test in the Emacs Lisp manual.
    Please take a look.

Can you please tell me where to look?