prayer flag

when a prayer flag flaps in the breeze, it is said that prayers on the flag are carried off by the wind to all beings. but what happens when you burn a prayer flag? do the prayers die? are small kittens tortured somewhere? is it sacrilegious to burn a prayer flag? (according to www.prayerflags.com, the proper way to dispose of an old flag is to burn it. hmmm...) what about pulling it apart one thread at a time, or shredding it in a paper shredder? is that OK as long as the fabric doesn't touch the ground?