Ahhh, so this is a guitar technique. I did a search and the concept of the drop 2 chord isn't that hard. It's just taking the next to last note of the chord and dropping it to the bottom. If you look at the chord on sheet music, it would be the second note from the top, hence the name "drop 2". Example:
CM7 = C-E-G-B
To make this chord a drop 2 voicing, take the G and move it to the bottom
CM7 drop 2 voicing: G-C-E-B
Fairly simple concept, not sure how useful it will be for keyboardists tho. Will have to play around with this some more.