This International Standard specifies a metadata system for describing multimedia content. It specifies the Description Definition Language (DDL) that comprises part 2 of the standard (ISO/IEC 15938-2).

The goal of this part of the MPEG-7 International Standard is to specify a language that will enable MPEG-7 users and developers to:

• create valid MPEG-7 description schemes and descriptors;
• develop tools such as editors and parsers for processing descriptions, description schemes and descriptors;
• generate refinements, extensions and modifications to the DDL.

This International Standard describes the features of the DDL. It defines the syntax of the DDL constructs and datatypes and provides optional (informative) examples that illustrate the application of the DDL to the specification and instantiation of MPEG-7 descriptions.