Does adding enum values or named bits for an object necessitate a revision of the corresponding OBJECT clause if the MIN-ACCESS is read-only?

["C. M. Heard" <heard@pobox.com>]

During the AD review of draft-ietf-atommib-rfc2495bis-05.txt it
became clear that Bert and I had slightly different ideas of when it
is necessary to enforce the following part of Section 4.9 the MIB
review guidelines document:

 - RFC 2580 should (but does not) recommend that OBJECT clauses
   specifying support for the original set of values be added to
   a compliance statement when enumerated INTEGER objects or BITS
   objects referenced by the compliance statement have enumerations
   added, assuming that no such clauses are already present.  This
   is necessary in order to avoid a silent change to the meaning
   of the compliance statement.  MIB module authors and reviewers
   SHOULD watch for this to ensure that such OBJECT clauses are
   added when needed.  Note that this may not always be possible to
   do, since affected compliance statements may reside in modules
   other than the one that contains the revised definition(s).

The specific issue for rfc2495bis was that new enum values were
added to the definitions of the objects dsx1LineType and
dsx1TransmitClockSource.  Here were Bert's comments (trimmed down to
essentials for brevity):

Bert>   .\DS1-MIB:181 [5] {named-number-added} warning: named number
Bert>     `dsx1E1Q50' added to type used in `dsx1LineType'
Bert>   .\DS1-MIB:181 [5] {named-number-added} warning: named number
Bert>     `dsx1E1Q50CRC' added to type used in `dsx1LineType'
Bert>   .\DS1-MIB:474 [5] {named-number-added} warning: named number
Bert>     `adaptive' added to type used in `dsx1TransmitClockSource'
Bert> Seems OK, given recycle at PS.
Bert> But should we not change the deprecated COMPLIANCE to exclude
Bert> the new additions?

where the deprecated compliance contained the following OBJECT
clauses:

             OBJECT dsx1LineType
             MIN-ACCESS read-only
             DESCRIPTION
                 "The ability to set the line type is not
                 required."

             OBJECT dsx1TransmitClockSource
             MIN-ACCESS read-only
             DESCRIPTION
                 "The ability to set the transmit clock source is
                 not required."

In my original review of rfc2495bis I did not request a change to
these OBJECT clauses since the new values do not increase the
minimum requirements imposed on an agent for compliance.  That is
because an agent meets the minimum requirements of the compliance
statement if it provides read access to these objects and does not
return (or accept) any values other than those specified in the
object definitions.  Since an agent that provides read-only access
to an object selects the values that will be returned, a SYNTAX
refinement does not change the minumum requirements, and so is not
strictly necessary.  At least that is my take.  Here is a different
point of view:

Bert> That is MIN-ACCESS right? So some implementations may provide
Bert> write access, and so an NMS could conclude even from the
Bert> deprecated compliance that it can SET those values, no?

Although this is not a terribly important point it would probably be
good for sake of consistency in our revoews to get consensus on how
we should handle it, and clarify the guidelines text if necessary.

Thanks,

Mike