Permission In Principle - Public forum - Planning Advisory Service (PAS)

Hi, I have received an application for permission in principle on previously developed land. The NPPG (Para 004 Reference ID: 58-004-20180615) includes  a table which shows that PIP applications can be made on land not defined as previously developed - the implication being that it cant be used for land which IS previously developed. This isn't however stated either in the original regs or the  NPPG (the later of the two so presumably the one to follow). How is everyone else dealing with this ?

Thanks