The spec (CSDL) points out that annotations can be used for describing data mappings: "A term can be used to ... map instances of annotated structured types to an interface defined by the term type; i.e. annotations allow viewing instances of a structured type as instances of a differently structured type specified by the applied term." [CSDL, section 14] Simple examples are provided by Example 38 and 86. Two questions.
Q#1 Has a service client URL-based access to a mapping from entity type A to B, so is there a way to construct a URL asking for a "B view" on an instance of A?
Q#2 Are the current possibilities sufficient to describe the mapping of deep documents, with multiple levels of hierarchy implied by chained traversals of associations?