A metadata model is a formal description of how metadata are structured to support the information needs of an organization. Like any data model, a metadata model can be described at a conceptual level, illustrating relationships between metadata items and the larger body of data around which they are generated; a logical level, reflecting the technical and operational parameters in which the metadata items exist; or from a physical perspective, specifying layout, file structures, and other characteristics. In more general terms, a metadata model is a representation of how an organization's metadata items relate to one another and to the larger body of data around which they are collected and generated. At a more detailed level, a metadata model maps and illustrates how data elements, metadata items, business rules, subsystems, data repositories, data flows, and information needs relate to one another. The type of system architecture used in the organization (see chapter 4) will strongly influence the appearance and logic of a metadata model.