An identifier is the representation within the language of items created by the user, as opposed to language keywords or commands. Some identifiers stand for dictionary objects, which are the objects you create- such as tables, views, indexes, columns, and constraints- that are stored in a database. They are called dictionary objects because Derby stores information about them in the system tables, sometimes known as a data dictionary. SQL also defines ways to alias these objects within certain statements.
Each kind of identifier must conform to a different set of rules. Identifiers representing dictionary objects must conform to SQL-92 identifier rules and are thus called SQL92Identifiers.