It's just a sus2 chord. The voicing you're talking about is this one:
--x--
--x--
--x--
--9--
--7--
--5--
The voicing is R, 5, 2. It's a triad with the 2 substituting for the 3. The one voiced above is an Asus2 chord (sometimes written as just Asus).
They've been used a lot since the 80s in alternative rock type stuff, especially for riffs. You can hear it pretty clearly in the riff for Message in a Bottle by the Police, and in the riffs for Satellite and Warehouse by the Dave Matthews Band. |