At present it seems that the de facto code for bitcoins seems to be BTC. There has been some discussion of this over on the forums and an entry on Wikipedia, but I thought I'd ask the question here to arrive at an easily recognised community answer.
So, if bitcoins ever became ratified as a currency under ISO 4217 (paywall, PDF) would it be given the code BTC? If not, then what other serious contenders are there?