ID3 tags: CM1?

(I'm asking this question here, rather than on the Receiver BBS, because I figure that more people will read it).

Last night, I resumed hacking on my Replacement Rio Server. It'll be written in pure C#. I'm currently hacking on the ID3 import code.

One of the tracks I've got (tagged with ID3v2.3.0) has what appears to be a 'CM1' tag in it. It appears to contain text.

Any idea what it is? According to my understanding of the docs, it's not a legal frame.

Mmm.. didn't exist when I wrote mp3tool either.
??

Sounds suspciously like Content Management stuff..

Nah, it contains what appears to be the name of the person who ripped the track.

ID3v2 tags (post 2.2, anyway) have four characters. What's the other one?

A null. That's why I don't think it's kosher. It does appear to be correct in every other way, though -- i.e. the length seems right.

It's not a biggy -- I'll just ignore it, I just wondered if anyone knew what broken-ass tagging program was generating it.

what appears to be a 'CM1' tag in it

"CustoM 1" perhaps?

-Mike

While I'm not saying someone who'd create a 3-letter tag in a 4-letter realm would be the brightest bulb, the ID3 spec expressly allows all tags starting with "X", "Y", or "Z" for playing around with. All others are reserved.