They have build numbers for the test rings. Otherwise, they've used names and numbers for new releases. The last one was November's Fall Update, version 1511 (f

They have build numbers for the test rings. Otherwise, they've used names and numbers for new releases. The last one was November's Fall Update, version 1511 (from the date) and the next one is August 2's Anniversary Update. Either way, the naming is essentially arbitrary, so they can change it however they like. The same Windows code, which has a long history, is going to continue into the foreseeable future...