Universal Core Semantic Layer

The Universal Core (UCore) is a central element of the National Information Sharing Strategy that is supported by multiple U.S. Federal Government Departments, by the intelligence community, and by a number of other national and international institutions. The goal of the UCore initiative is to foster information sharing by means of an XML schema providing consensus representations for four groups of universally understood terms under the headings who, what, when, and where. We here describe a project to create an ontology-based supporting layer for UCore, entitled ‘Universal Core Semantic Layer’ (UCore SL), and describe how UCore SL can be applied to further UCore’s information sharing goals. Index Terms – Ontology, Data Integration, Semantic Technology, OWL DL, Universal Core I. THE UNIVERSAL CORE The Universal Core (UCore) [1] is a US Federal Government information sharing initiative that is supported by the US Departments of Defense, Energy, Justice, and Homeland Security, by the Intelligence Community, and by a large number of other national and international agencies. UCore supports the principles of the Department of Defense (DoD) and Intelligence Community (IC) Data Strategies by defining a small set of common data elements that are implemented in a lightweight information exchange schema that is shared across multiple agencies. The prime focus of the UCore initiative is messaging. UCore is designed to promote information sharing across multiple message domains by means of a simple XML message format built on a taxonomical structure comprising four groups of terms under the headings who, what, when, and where. Table 1, below, represents the taxonomy as released in UCore Version 2.0, which is the version upon which we focus in what follows. Table 2 represents the relations contained within the UCore 2.0 xsd:schema. The UCore strategy is to require message-creators to construct for each message a digest, a summary built out of a restricted vocabulary of UCore terms, and to link elements from the message payload to this digest. Developers of information systems are encouraged to use these terms wherever practical in order to realize the goal of facilitating automated sharing of information within and across agencies. To reap maximal benefit from its messaging resources, participants in the UCore initiative offer validation processes and tools intended to promote machine understanding of message content, thereby enabling multiple different types of information retrieval, reasoning and consistency checking. The UCore taxonomy consists of terms (such as ‘Person’ or ‘Organization’) which are universally understood in the sense that they require no domain-specific expertise for their understanding. The taxonomy can thereby be shared by many different types of users, and thus it provides the opportunity for interoperability over many different sorts of domainspecific exchanges. As M. Daconta expresses it: if I have a UCore-wrapped National Information Exchange Model [NIEM] message from Immigration and Customs Enforcement about illegal immigrants wounded during criminal activity and I have a UCore-wrapped Health and Human Service Department message on visitors to emergency rooms, I have enabled immediate cross-domain search. ... UCore is a process of extracting cross-domain commonality from your message flows, thereby massively broadening the possible adoption and use of your shared information. In information sharing, adoption by consumers is the key value metric. [2] The UCore 2.0 taxonomy in its current form is well adapted to realizing this strategy of information sharing on the basis of universally understood terms. UCore 2.0 as a whole, however, still has a number of problems, including a mismatch between this taxonomy and UCore’s larger XML schema. The latter includes a number of elements that are not represented in the taxonomy, including spatial and temporal terms: GeoLocation: A physical location with coordinates, or a simple geospatial region; TimeInterval: An interval in time, defined by two instants in time. Since these elements do not have a corresponding representation in the taxonomy, their intended semantics remain implicit, and no straightforward way exists to link them to, say, spatio-temporal ontologies. II. UCORE AND THE ARMY NET-CENTRIC DATA STRATEGY UCore is designed not only to support messaging and the retrieval and analysis of message content. It is also built in such a way as to support interoperability of information systems of a variety of different types. The strategy is to have UCore serve as the consensus starting point for the construction of successive layers of more inclusive artifacts,