AWS does not publish the is/was changes to their brazing specifications. Is reading through an 8 page spec once every 5 years really a burden? You are strongly encouraged to find a quiet place and read through the entire document and keep a checklist to verify you meet all the requirements. That said, in general, if you were meeting the 1999 versions you will meet the 2007 versions, but there were numerous tweaks made throughout and it only takes one small miss to end up with an audit finding and rejected parts. The AWS C3 Brazing and Soldering Committee is working on revisions to the 2007 versions so plan on having to read it again in another year. If anyone has anything they would like to see changed in C3.4, 3.5, or 3.6, or the other brazing specifications, this forum would be a good place to post it.