Secured E-mail standard?

Has a proposal been made to officially adopt a header field in standard
Internet mail messages that would essentially include security signature
information?  Something like:

        X-Security-Type: PGP 1.0
        X-Security-Code: asdui&Dh1daOFajsFNOA...etc.

These generic field names would allow for various types of security methods.
Most important, would make it a lot easier for smart e-mail systems to
recognize secured e-mail, with the option of allowing the user to filter
out such fields when reading text.  The current scheme of having to
"frame" the content (plain text) and add the PGP signature is distracting.

 /\/\  Morgan Davis Group (619/670-0563)
/ /__\  Internet: mdavis@pro-sol.cts.com