RFC 2938 (rfc2938) - Page 3 of 18

Identifying Composite Media Features

RFC 2938          Identifying Composite Media Features    September 2000


   feature set reference
            a brief construct that references some feature set.  (See
            also: "dereference".)

   feature set tag
            a name that conforms to the syntax of a feature tag [2] that
            is used to denote a feature set rather than a single
            feature.

   resolution
            (See "dereference").

   This specification uses syntax notation and conventions described
   in RFC 2234, "Augmented BNF for Syntax Specifications: ABNF" [3].

       NOTE: Comments like this provide additional nonessential
       information about the rationale behind this document.  Such
       information is not needed for building a conformant
       implementation, but may help those who wish to understand the
       design in greater depth.

2. Motivation and goals

   The range of media feature capabilities of a message handling system
   can be quite extensive, and the corresponding feature set expression
   [1] can reach a significant size.

   A requirement has been identified to allow recurring feature sets to
   be identified by a single reference value, which can be combined with
   other elements in a feature set expression.  It is anticipated that
   mechanisms will be provided that allow the recipient of such a
   feature set reference to discover the corresponding feature set
   expression, but any such mechanism is beyond the scope of this
   specification.

   Thus, the goals for this proposal are:

   o  to provide an abbreviated form for referencing an arbitrary
      feature set expression.

   o  the meaning of (i.e., the corresponding feature set expression) a
      feature set reference should be independent of any particular
      mechanism that may be used to dereference it.

   o  to be able to verify whether a given feature set expression
      corresponds to some feature set reference without having to
      perform an explicit dereferencing operation (i.e., without
      incurring additional network traffic).



Klyne & Masinter            Standards Track