I'm a little confused about the term "SPD".

Here's an SPD pedal that uses the big triangular cleat:
http://www.performancebike.com/bikes...LAID=859291133

Here's an SPD that uses the MTB style cleat:
http://www.universalcycles.com/shopp...ils.php?id=710

I thought the term SPD refered to the typical road pedal with the triangular cleat.