We present the syntax and semantics of a modular ontology language $\logic{SHOIQP}$ to accomplish knowledge integration from multiple ontologies and knowledge reuse from context-specific points of view. Specifically, a $\logic{SHOIQP}$ ontology consists of multiple ontology modules (each of which can be viewed as a $\logic{SHOIQ}$ ontology) and concept, role and nominal names can be shared by ``importing'' relations among modules. The proposed language supports contextualized interpretation, i.e., interpretation from the point of view of a specific package. We establish the necessary and sufficient constraints on domain relations (i.e., the relations between individuals in different local domains) to preserve the satisfiability of concept formulae, monotonicity of inference, and transitive reuse of knowledge.