1. A storage medium for storing data for access by an application program being executed on a computer system, comprising: a first object stored in the medium to provide a first group of services related to interacting with a hierarchical namespace; a second object stored in the medium to provide a second group of services related to associating information with the first object; a third object stored in the medium to provide a third group of services related to describing attributes of the second object, wherein the third group of services include a schema that is inheritable by a child object that provides a group of services related to describing attributes of an object related to the child object; wherein the first object is logically part of a virtual content repository (VCR) and includes a reference to a parent object in the virtual content repository (VCR) that enables traversal of the virtual content repository (VCR) and a path that uniquely specifies the first object's location in the virtual content repository (VCR), and wherein the virtual content repository (VCR) represents, using an application program interface (API), a plurality of content repositories logically as a single content repository encompassing the plurality of content repositories from the application program's standpoint; wherein each content repository in the plurality of content repositories implements a service provider interface (SPI) including a set of interfaces and services to plug the plurality of content repositories into the virtual content repository (VCR); and wherein the API and the SPI share a content model that represents content of the plurality of content repositories as a hierarchical namespace of nodes.