NEW YORK (CNNMoney) -- The Internet Corporation for Assigned Names and Numbers said Friday it approved the .xxx domain for adult web sites after years of nixing the idea.

A spokesman for ICANN, which holds jurisdiction over top-level domains, confirmed the go-ahead.
http://money.cnn.com/2011/03/18/tech..._xxx/index.htm

Does this mean that all XXX sites will be required to use that extension or will it only be an option to select that extension?