BrowserUk, I was thinking along the same lines on the regex, but you beat me to it and you've got better regexes than what I was coming up with.

Assuming that OP is concerned about the formatting (the two underscores in the first 'word' and starting strings for the next two 'words), I think a slight modification of your second regex could work to meet that need. Something like:

m[CDC_\w+?_\w+(?:,\s+DDC(?:S|R)MR\w+){2}]
[download]

Of course, I haven't tested that, so I wouldn't be surprised if someone was able to point out problem(s) in that regex.