I found this on a map to day http://www.openstreetmap.org/?lat=48.523812&lon=9.046796&zoom=18&layers=B000FTF Namely the short streets next Herrenbergerstraße. They are ment to symbolize single parking spaces parallel to the street. It looks strange on the renderer (yes i know this should be no argument) and I belive a tag could store that information way better. Are there proposals for tags which indicate it and when and how long and how expensive parking is allowed, and how the parking spaces are orientated relative to the street?
http://wiki.openstreetmap.org/wiki/Tag:amenity%3Dparking .
But there is not yet a proposal for the orientation, but i think that with a way tagged amenity=parking, people will get the point. But then you won’t get a P symbol.