I haven't seen exactly what you're talking about, but it sounds like something different. There's a difference between the "Digitally originated graphic" that Andy is talking about, which is just the station logo, and what I suspect you're talking about, which I usually hear referred to, aptly, as a "screen bug" (I can't stand those things).

I think "digitally originated graphic" is too broad a term for such a specific use as a station ID on a TV broadcast. Wouldn't everything on the screen be described as a graphic of digital origination? I guess if it was shot with a camera, it didn't "originate" as a digital thing, but all computer-generated graphics, transitions, news crawls, etc, would be of "digital origination."

Sorry for the nit-picking