14. The computer-readable storage medium of claim 11 , further comprising defining the ML namespace using the prefix, wherein the prefix maps to an extensible markup language namespace, and wherein the definition file maps the extensible markup language namespace to a common language runtime namespace and the assembly.
11. A computer-readable storage medium having computer-executable instructions for mapping a tag in an ML document to a common language runtime class using common language runtime namespaces, the instructions comprising: evaluating a tag in the ML document, wherein evaluating the tag comprises reading a prefix associated with an ML namespace when the prefix is present; detecting a definition file location attribute associated with the tag in the ML document; fetching a definition file from a location specified by the definition file location attribute, wherein the definition file includes: a schema that limits the scope of attributes in the definition file, a list of assemblies that references the definition file, a list of common language runtime namespaces associated with the list of assemblies that references the definition file, wherein each common language runtime namespace includes a list of common language classes associated with the common language runtime namespace, and an installation tag that includes a uniform resource identifier for installing assemblies of the list of assemblies; resolving the common language runtime namespace related to the tag within the definition file to establish the common language runtime class associated with the tag; and finding an assembly that includes the common language runtime class such that the tag is mapped to the common language runtime class, wherein the assembly comprises common language runtime classes of functions associated with the common language runtime namespace.