Add this tale to the growing lore of the inscrutable iPhone app approval process: Apple has rejected an application from Nine Inch Nails front man and entrepreneur extraordinaire Trent Reznor, possibly because it can stream a song that contains a single curse word — even though the song is for sale on iTunes. But, actually, we really don’t know why.

Confused? So’s Reznor. And really, really pissed. In a scathing post to his band’s message board, Reznor lashed out at Apple for its obscenity policy and for sending him a confusing e-mail that did not make clear what needs to be done so that the app can be approved. The choice word he has for Apple now happens to be the same one in banished tune, “The Downward Spiral.”

“‘The Downward Spiral,’ the album, is not available anywhere in the iPhone app,” wrote Reznor. “The song ‘The Downward Spiral’ I believe is in a podcast that can be streamed to the app,” he continued. “Thanks, Apple, for the clear description of the problem — as in, what do you want us to change to get past your stupid fucking standards?”