At VIE for example, a SID is named for its terminal waypoint, its issue and its departure runway. A departures leave from Rwy. 11, B departures from 16, C from 29 and D -you guessed it, I am sure - from 34. In the rare instance of two different routes from the same runway to the same fix, the secondary one is appended with an X instead.
So the ABLOM 5D will be the 5th revision of the ABLOM-bound Rwy. 34 departure.
At other fields, other systems may be used: at LEJ, departures from the northern runway (08L/26R) often have an N and those from the southern one carry a S (TORPU 2N or TORPU 2S for example).