Civil Service pension distribution code?

I receive a monthly Civil Service pension from OPM, and my 1099-R shows "7-Nondisability" in block #7. That is not a choice in the drop down menu of choices.  Leaving it as No Entry doesn't work, and if I choose 7 it leads me down a road that would suggest that I received my entire gross distribution in a lump sum.  So what do I enter for this distributon code so that I can continue? Extremely frustrating..