The Layered Multimedia Data Model (LMDM) aids in the specification of multimedia compositions by dividing the problem into smaller, more manageable pieces. In this paper we describe the lower two layers of the LMDM, the Data Definition Layer, which allows the specification of multimedia objects in a database, and the Data Manip- ulation Layer, which allows the specification of tempo- ral structures built from those objects. Several examples demonstrate the advantages of the layered paradigm: sim- ple specifications, and modular, reusable components.