There is a huge issue going on with this right now.. I don't know if we're talking Reg or Reserve, and since I have no knowledge of how UTPNCM works for the reg guys, I'll leave it alone. What I do know is this: before, UTPNCM was not available to the reserve guys coming over to officer in the reg force. You took your cut in pay, down to OCdt level whatever (for me it was about $1250 a month gross), lost your rank and any leave entitlements etc etc. And of course you did this with a smile on your face because you were getting free education. A few intrepid individuals through the years decided that this wasn't right, that their reserve time should count the same as another person's reg time. Redresses went in, from my research they were all found for the grievor, and a load of backpay was issued. Someone up above took note of this and decided it wasn't right, and in 2005 ADM-HR(Mil) released Administrative Instruction 07/05, which basically means that from 2005 onwards if you join the regs as an officer from the NCM reserve world, you will be treated as a UTPNCM applicant. Details I'm not sure about but anyone who this matters to will look up the document and can read it for themselves. Anyone who joined in FY 06 is entered under the new rules, apparently applicants from FY 05 have been dealt with already (ie issuing back pay and pay rates based on prev service), and they are working backwards to FY 00 to deal with the rest of us. From what I've been told from a friend, once you get on the OCDT Pay level "D" scale, you don't go up in pay again until you get comissioned. He was a Sgt in the reserves, and with his previous service he got adjusted to a significant pay level with a load of backpay, after being dropped in rank to OCdt. This was determined from his previous service, basically adding up his class A/B/C time and working out what the reg equivalent would be.
I'm not a clerk and I have no RMS background, so take what I say with a grain of salt, especially since I'm giving second hand info. I think the reason there are 10 IPC levels to OCDT/D is so that they can cover all the possible rates of pay for UTPNCMs from privates up to sgts. I'm guessing the WOs and above are generally CFRs so they would go to their appropriate rank? Just a guess.
Anyways I hope that's not too confusing, I've been looking fairly deeply into this for the last year or so and I think I understand most of how it works. Again, don't take what I say as gospel, but this is what I've seen.