  We investigate the data complexity of the satisfiability problem for the very
expressive description logic ZOIQ (a.k.a. ALCHb Self reg OIQ) over
quasi-forests and establish its NP-completeness. This completes the data
complexity landscape for decidable fragments of ZOIQ, and reproves known
results on decidable fragments of OWL2 (SR family). Using the same technique,
we establish coNEXPTIME-completeness (w.r.t. the combined complexity) of the
entailment problem of rooted queries in ZIQ.
