Development for the National Geologic Map Database

Science language vocabularies are being constructed for use in the U.S. National Geologic Map Database (NGMDB), to provide geologic data to users in government, business, academia, and the general public in a consistent data structure, using consistent descriptive terminology or science language. These terms and defi nitions are used to classify observable or inferred facts or events, and to assign values for properties in descriptions. The vocabulary makes pre-defi ned terms available to apply in descriptions without having to reconstruct the entire description denoted by the vocabulary term. Terms within a controlled vocabulary may be atomic or analyzable. The atomic terms are irreducible in the database environment; they are either numbers, or terms defi ned by narrative text. The text defi nition is meant for a human user, and is not amenable to automated analysis. Analyzable terms are specifi ed by combinations of properties and relationships according to some formal description structure. Analyzable terms may be compared, using the values of the properties in their formal description. The atomic terms in a vocabulary may represent complex concepts that could be represented by description schema. Implementation of formal descriptions for terminology associated with a concept allows users to develop alternate or more specifi c terminology for concepts that may interoperate with other systems by using automated description comparisons (Description Logic). The unifying feature of the NGMDB is a common conceptual model and terminology system. To function as a part of the NGMDB, individual databases must conform to, or interoperate with, the common conceptual model and shared terminology. The simplest route to NGMDB conformance is to use the standard science vocabularies. If desired, users can build their own vocabularies, but in order to be NGMDB conformable, user-defi ned vocabularies will need to: 1) defi ne the scope of their vocabulary; 2) provide text defi nitions of each vocabulary term; 3) build formal defi nitions rooted in the standard science vocabulary, using description schema from the common conceptual model, and a standard, well documented syntax; and 4) provide a correlation of each term with the most specifi c subsuming term from the standard vocabulary.