Eh, what? PPR does not mean, and never has meant, 'Prior Permission Radio'. It means Prior Permission Required and that means by telephone beforehand.
It use to be that the phrase used was Prior Permission Only - PPO - but this got changed some considerable time ago to PPR. As far as I am concerned the two mean the same thing. Show me anywhere in the AIP where PPR and PPO are used?
The fact that some airfields are happy with PPR over the radio or even not all does confuse the issue. Why don't you speak to them and see if they'll get their AIP entry change which will eventually get swept up into the guides, or those not in the AIP, with the guides directly.
There is no confusion.