http://blogs.msdn.com/marcelolr/archive/2008/08/21/metadata-for-ado-net-data-services.aspxADO.NET Data Services have a "magic" resource, called $metadata . This entry point returns a CSDL document, which is generated as described on this MSDN page . Why CSDL? Well, it turns out that it's a great language to give a high-level description ofen-USCommunityServer 2.1 SP1 (Build: 61025.2)