Unrecognized critical control & referrals

["Kurt D. Zeilenga" <Kurt@OpenLDAP.org>]

RFC 2251, 4.1.2:
   If the server does not recognize the control type and the criticality
   field is TRUE, the server MUST NOT perform the operation, and MUST
   instead return the resultCode unsupportedCriticalExtension.

There seems to me the need for an exception to the MUST to allow
a server to return a referral instead of unsupportedCriticalExtension.
If the request would, if the control was not marked critical,
have returned a referral result, shouldn't that same referral be
returned when the control is critical?

Kurt