Here is a double stop lick from Pink Floyd's David Gilmour. This is from the intro solo on "Wish You Were Here".

The red number is the note that you should use as your guide when playing the lick in other keys. In this case the red note is a G. This lick is in the key of G major.

Because of the open string you will find this lick more difficult to transpose into other keys. Here is how you would play this lick in the key of A. You since there is not an open string you will have to eliminate the pull of that was in the original G major version.

For more information on how to read this, check out the lesson on reading Internet tablature.

This lick comes out of a G major pentatonic scale. The open 3rd string is the same note as the 5th fret on the 4th string.

The notes in red are the G notes (the root of the scale).