Semantic interoperability through shared ontologies aims to ensure the semantic soundness of exchanges of services and data among distributed information systems (ISs). Collaboration via shared ontologies, however, requires that the local ontology of every co-operating IS be explicit. Unfortunately, common IS requirements specification methods are not geared towards producing the local ontology of an IS; they usually translate requirements into procedural notations that make a local ontology largely implicit in the software code. This paper presents a method for eliciting IS requirements and specifying them declaratively, in a way that makes explicit the local ontology. The resulting declarative requirements constitute explicit metadata that can be used to support semantic interoperability as well as enterprise modeling and knowledge management. We have already successfully applied our method to knowledge-based systems (KBSs). Since KBSs are also ISs, albeit more complex ones, our method offers a solid basis for creating ISs whose local ontologies are explicit.