e--2-----5-----7-----9----14------14-----------------------------------
b--3-----6-----8----10----15------15-----------------------------------
g--2-----5-----7-----9----14------14-----------------------------------
d------------------------------------------------------------------------
a------------------------------------------------------------------------
E------------------------------------------------------------------------

and the third 12 plays these chords:

e--------------12----12---------14-----14-------------------------------
b--7-----8-----12----14---------15-----15-------------------------------
g--7-----7-----12----14---------14-----14-------------------------------
d--7----10---------------------------------------------------------------
a------------------------------------------------------------------------
E------------------------------------------------------------------------

Now one 12 stops playing and one 12 plays these chords
while the second 12 plays the same chords but with an open D-string
instead of a second fret D.
e--0----0-0--2------2-2--0---0-0--2--2-2--3--3-3-0--0-0--3--3-3--2------
b--3----3-3--3------3-3--3---3-3--3--3-3--3--3-3-3--3-3--3--3-3--3------
g--2----2-2--2------2-2--2---2-2--2--2-2--2--2-2-2--2-2--2--2-2--2------
d--2----2-2--2------2-2--2---2-2--2--2-2--2--2-2-2--2-2--2--2-2--2------
a-----------------------------------------------------------------------
E-----------------------------------------------------------------------