Ah yes, I'd forgotten about that.  DIMMs don't
do that, at least in my
 experience; they are wiping contacts, very much like PCI or ISA slots.
 (I speculate that this is because while, like SIMMs, they have
 connection pads on both sides, they also, unlike SIMMs, connect
 different things to different sides' pads - and the pressure connectors
 SIMMs use aren't very well suited to that sort of pinout.) 
OK. In which case I'd class a DIMM socket as a particular type of edge
connector (admittedly if I wanted to buy one, I'd ask for a 'DIMM socket'
and not 'An edge connector with <foo> number-of-pins at <bar> pitch').
-tony