Explicitly disallow certain XML constructs (for CSDL, ATOM) to enhance OData security

Considering the XML security vulnerabilities detailed in:

http://stackoverflow.com/questions/1906927/xml-vulnerabilities

it might be prudent to explicitly disallow certain XML constructs (DOCTYPE, ENTITY definitions and processing instructions) in ATOM, CSDL and any other XML documents used by OData.

Specifically, a server receiving an XML document from the client, and a client receiving a document from the server, would be "permitted to ignore" (or preferably, "required to reject"):

(1) XML DOCTYPE definitions
(2) XML ENTITY definitions
(3) XML processing instructions