I want to suggest that @cert doesn't belong in att.responsibility. In implementing FR 465 I was originally going to add @source to att.responsibility and remove att.source. But there are elements that use att.source (like egXML) for which @cert makes no sense at all. In the end I made att.responsibility a member of att.source, but I think it would be better to divorce @cert from @resp and perhaps still combine @source and @resp into one class. I can see @resp being useful anywhere @source is (with the possible exceptions of q and quote) but @cert is only going to apply to things which are (on some level) guesses. Arguments against? For?