Thanks for your answers!
I'm still not sure if I understand this 100 % yet. A full scale deflection is 0.3 NM from the centerline, and the calculated position should be within 0.3 NM of your actual position? RNP, is, as I understand, based on the accuracy of the navigational equipment and how accurate the crew can navigate, flight crew errors. So how accurate should the flight crew be able to navigate? Be able to maintain within half scale deflection? Three-quarter scale deflection?