In message , at 18:08:12 on Tue,
26 Apr 2016, Graham Murray remarked:

As no unattended parking is allowed by the Police, what's the
difference between a Waiting and a Parking restriction?

Whether or not the engine is turned off, and for automatics whether it
is in 'neutral' or 'park'?

Waiting has nothing to do with whether the vehicle is occupied,
otherwise there could be no 20-minute general exemption for people doing
"loading/unloading" in the absence of a specific additional prohibition
for that.
--
Roland Perry