The last two posts start with "I just spoke with somebody at the IRS ...", and each has the exact opposite answer. That's because the IRS isn't infallable. In fact, they get it wrong a lot of the time. They consider telephone advice that is correct 80% of the time to be GOOD. I don't know about you, but I consider that awful. Anything they say over the phone they can't be held accountable for. Anything they put into print you can rely on in court. I would take any advice provided over the phone with a grain of salt.
I have not yet had any tax return rejected by the IRS for using "NRA" for the spouse. I do over 200 returns a year, with probably about 1/4 having NRA spouses. Beleive me, if I were making a mistake, my clients wouldn't let me hear the end of it; so it's a-okay to put "NRA". I know Guya is in a similar situation (though I haven't a clue how many returns he prepares, or even if he's a he), in that he does loads of "NRA" spouses without a hitch.
Some computer programmes will reject "NRA", however. If you are using a tax programme that won't let you finalize the return using "NRA", consider filing a paper print-out of the return rather than the computerized online version.