schema DDL
2.According to a set of predefined conversion rules from ontology to RDB schema, an conversion algorithm and the XML representation format for element mappings between ontology and RDB schema (Onto-RDB), O2DDesigner automatically generates RDB schema (SQL DDL statements) and Onto-RDB element mappings data in XML format based on the inputted domain ontology.
3.It is designed to be used for reservoir description, supported by VAX/VMS operating system, using network data medel. The base schema is de-fined by data tacribing language (DDL).

