This report proposes a Reference Model (RM) for database management system (DBMS) standardization. A Reference Model is a conceptual framework whose purpose is to divide standardization work into manageable pieces and to show at a general level how these pieces are related with each other. The proposed RM comprises a Data Mapping Control System (DMCS) that retrieves and stores application data, application schemas, and data dictionary schemas. This DMCS is bounded by two interfaces: the Data Language (DL) interface which defines the services offered by the DMCS to various Data Management Tools (DMT), and the internal Data Language (i-DL) interface which defines the services required by the DMCS from the host operating system. This report suggests two candidates for standardization: the DL and the i-DL.