This paper analyzes different options for semantic database schema definition and describes a presentation format XSDL. Presentation of semantic database in a certain format implies that the format fully preserves the database content. If the database is exported to this format and then imported back to the database engine, the resulting database should be equivalent (Rishe, 1992) to the one that was exported. XSDL is used for information exchange, reviewing data from databases, debugging database applications and for recovery purposes. Among other requirements that XSDL meets are support of both schema and data, readability by the user (XSDL is a text format), full preservation of database content, support for simple and fast export/import algorithms, portability across platforms, and facilitation of data exchange.
