model, store data that's retrieved from a database server, and communicate with the server.&nbsp; The access layer classes are DBDatabase, DBRecordStream (and its subclass, DBRecordList), DBExpression, DBQualifier, DBValue, and DBBinder.&nbsp; The most important access layer protocols are DBEntities, DBProperties, and DBTypes.&nbsp; (There are other access layer protocols, but they're used to complete the implementation of the access layer classes.&nbsp; As such, they're referred to in the specifications of