The "method" MUST refer to an authentication method declared in this
memo, or in a subsequent one, or to an authentication method name
assigned by IANA.
Given that there will be an IANA registry that includes the ones in
this document and future documents, this is more succinctly as:
The "method" MUST refer to an authentication method declared in the
IANA registry.
--Paul Hoffman, Director
--Domain Assurance Council
_______________________________________________
NOTE WELL: This list operates according to http://mipassoc.org/dkim/ietf-list-rules.html