642 at the terminal stop at Per-Albin-Hansson-Siedlung, where interchange is made with the 17A bus.

There was previously another loop with a very similar name at Per-Albin-Hansson-Siedlung Ost, between Rothneusiedl and Oberlaa-Therme Wien. However, this was a new loop created to allow the service to be curtailed for U1 line construction in 2014.