Are all copper cables virtually oxygen free?

I've been talking to folks at Storm Products and Allied Wire and Cable about ac cables -- both distribute and custom build various wires and cables. According to them, newer techniques among American manufacturers virtually eliminate any oxygen in copper. They could not speak to other manufacturers since "not a lot of wire is imported" -- presumably because of the cost dynamics. That means that, for all practical purposes, Romex has similar OFC characteristics to all the cables that are being touted. Of course, there are other sonic characteristics like crystal size (ala Harmonic Tech)and other non-copper impurities. But, is OFC a fait accompli for all cable? What does that mean? I'm way out of my range of expertise here but was wondering if anyone else has heard this and/or knows the implications. Thanks.