I Have To Ask This....

I believe so. Just like EF = XF.

PR-PF are pretty much interchangeable, even though I believe that PR is correct and is the abbreviation I use exclusively for proof.

sweet thanks guys

As noted similar to XF or EF. I wonder if this is some sort of holdover from the good old days of only a G, F, Unc and/or Pr. After those good old days we ended up with all sorts of AU's, AG's, EF's, XF's and on and on and on.
I sometimes wonder why not just go to 1, 2, 3, 4 and all the way up to 70 or maybe 100. Don't know who really started that G stuff for Good when the coin that is G is more likely Garbage.
May have been originally G for Garbage, F for Funny, you for Usable.

But Shelodn's "70 point scale" was not a grading scale, it was a relative pricing scale and it was only for early date large cents. First you had to grade the coin, then you looked up how much a coin in Poor for that variety was worth. Then by multiplying that value by the multiplier for the grade you arrived at the value of the coin. Sheldon thought he had discovered a "natural law" of cent values and that as prices rose all you would have to do is raised the value of the Poor coins and that would adjust all the other values because the relationship between the grades wouldn't change. What Sheldon failed to appreciate was that as more collectors entered the hobby they would naturally gravitate toward the best coins they could afford. This put increasing pressure on the higher grades. Supply and demand took over, the higher grades moved up faster and the ratios between grades changed. For years EAC kept trying to tweak the values of the Poor coin, and apply new adjustment rules to try and make the 1 to 70 multipliers fit again. (Anyone who understood basic economics should have known that it couldn't be done.) Finally in 1972 EAC admitted defeat and chucked the 1 to 70 pricing concept. Five years later the ANA stuck those now meaningless pricing numbers onto the standard grades that had been in use for close to fifty years and the "Sheldon Grading scale" was born. And the numbers ARE meaningless. Any group of numbers would have worked just as well as long as they were arranged in order either ascending or descending.