I'm puzzled by that. The captioning for non-digital TV has minimal error detection (the bytes sent in Line 21 are "odd parity," i.e. each byte has an odd number of bits set to 1) and no error correction. If either byte of the two bytes sent at a time fails parity check, they're both tossed, which is why you often see two letters missing from words. Many errors don't change parity, so they escape detection--which is why you often see weird accented characters sprinkled in captions where they shouldn't be.
Digital TV captioning, though, is a part of an MPEG-2 data stream, and I'd have thought it would have a decent level of error correction built in.
Check out this article in TV Newsday; TV stations now^H^H^Hsoon will have to post contact info on their web site for someone to deal with captioning problems, and stations have to respond to complaints within thirty days. I wonder whether that applies to cable operators as well as stations?
UPDATE: Drat! Those rules aren't yet in effect; see the FCC's closed captioning web page for details and info on how to file complaints.
