What does D mean on bus timetables in Ireland?

 Some Irish bus timetables, and especially Bus Éireann timetables, have stops that are labelled "D".

For example, the current Route 51 Galway - Cork regional bus timetable has the stop at Shannon Airport departures gate marked "D" on all services, while the Arrivals Gate times are marked P.

This means that the stop is "drop-off only", that is, people can get off the bus here, but cannot get on.

Usually this is because there is another nearby stop which makes more sense for people to get on the bus at.  In the example above, this is the Shannon Airport Arrivals Gate, which is "pick-up only".   Or there may be another local bus for people travelling from this bus-stop to the next one, and it is best that regional buses are not slowed down by loading and unloading short-journey passengers.

Usually, the bus driver will not provide any chance for passengers to get on at these stops:   they will only stop if someone wants to get off, and they may pull up slightly in front of or behind the stop.  Often they may only open the doors just long enough for people who want to get off the bus.