Three generations in type I compactifications

Generalizing the recent work on three-family type I compactifications, we classify perturbative type I vacua obtained via compactifying on the T⁶/Z₂⊗Z₂⊗Z₃ orbifold with all possible Wilson lines. In particular, we concentrate on models with gauge groups containing the standard model gauge group SU(3)_c⊗SU(2)_w⊗U(1)_Y as a subgroup. All of the vacua we obtain contain D5-branes and are nonperturbative from the heterotic viewpoint. The models we discuss have three chiral families. We study some of their phenomenological properties, and point out nontrivial problems arising in these models in the phenomenological context.