Maybe (ahem... yet another... fool I am...) "via" URI scheme ?
Say :
<< via://[optional date-info][:ns-document-URI-scheme, defaulting to
http]@rddl.org/rddl2/ >>
then, either of
<< via://[date-info]@rddl.org/rddl2/ >>
or
<< via://[date-info]:/rddl2/ >>
could easily be bound to :
<< http://rddl.org/rddl2/[date-info] >>
(where [date-info] is, at the level of the user-agent processing "via:"
URIs, restricted to be ISO date variants)
[uri-schemes] "URIs are noun phrases, not verb phrases"
http://www.w3.org/Addressing/schemes.html
PS :
"Via" (the latin word - see [uri-schemes]) meaning sth like :
"the road to get to... the identified namespace in space (rddl.org) and time
(date-info)" ;o)
Rgds,
--CJ
