Prasad,
Section 4.1 of [Models] says: "Implementors should note that future versions of this document may expand these definitions to include additional terms. Terms whose identifier begins with "X-" are reserved for private experiments, and are followed by <SP> and <qdstrings> tokens."
Why is there a restriction that the X-<tag> be followed by qdstrings alone. Shouldnt implementations be allowed to return binary values as well here.
The restriction is so that implementations not recognizing the private experiment can skip over and ignore the extension if they happen to encounter it.
Regards, Steven