  Recently, we discussed the first example of a phenomenologically realistic
intersecting D6-brane model. In this model, the gauge symmetry in the hidden
sector is USp(2)_1 x USp(2)_2 x USp(2)_3 x USp(2)_4. However, we find that the
USp(2)_1 x USp(2)_2 gauge symmetry can be replaced by an U(2)_{12} gauge
symmetry, and/or the USp(2)_3 x USp(2)_4 gauge symmetry can be replaced by an
U(2)_{34} gauge symmetry since the USp(2)^2 stacks of D6-branes contribute to
the same Ramond-Ramond tadpoles as those of the U(2) stacks. Thus, there are
three non-equivalent variations of the hidden sector, and the corresponding
gauge symmetries are U(2)_{12} x USp(2)_3 x USp(2)_4, U(2)_{34} x USp(2)_1 x
USp(2)_2, and U(2)_{12} x U(2)_{34}, respectively. Moreover, we study the
hidden sector gauge symmetry breaking, discuss how to decouple the additional
exotic particles, and briefly comment on the phenomenological consequences.
