Minimum size for on-screen disclaimer?

I'm asking this question for a friend, who has a client. This client wants to see (for whatever reason) the FCC rule regarding the minimum size of an on-screen disclaimer. Now, I know (in the same sense that I know I put my keys on the table when I came home) that the answer is 4% of active picture lines, or 20 scan lines tall for NTSC. But I can't for the life of me remember where I learned that, nor can I google up an authoritative source for it.

Any of you folks know where I can get some definitive-ish information on this?

Is there really such a rule from the FCC? If the FCC had one it would be overruled by whichever station or network or distributor was releasing the content, wouldn't it?

Noah

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There are rules about this - minimum font sizes, time on screen, no distracting influences on screen at the same time, but it's pretty unclear really. There's a thread on the Cow here [forums.creativecow.net]