What is a EURO card?

A EURO card (OEM4, OEMV or OEM6) simply means it is a euro form factor card, which is the same form factor as OEM2 with a large 4 inch edge connector on the side. In the case of the newer product, these are mounted onto a EURO board. These were meant to be mounted in a PC stack.

More information here:

http://en.wikipedia.org/wiki/Eurocard_(printed_circuit_board)