9-8-2012 Milndollarbabe: IMO the rv rate is gathered from a variety of resources and I'm quite sure there is a formula that is used. Debt relieved, natural resources, oil reserves, gold, etc.
I don't know what the formula is but I'm sure there is one and a range has been given to the IMF for approval. Budgets can be ammended and changed. I wouldn't be surprised that it is calculated with a basket of currencies to help it maintain its stability in this volatile time of economic chaos.
Stability is the main concern for when its to pop that it can and will be maintained and if its pegged to a basket that would help achieve such.