Re: [Disman] draft-ietf-disman-event-mib-v2-06.txt: Issue-1 -> "MAY not"

["Randy Presuhn" <[e-mail]>]

Hi -

> From: "Benoit Claise" <[e-mail]>
> To: "Disman (E-mail)" <[e-mail]>
> Sent: Monday, July 18, 2005 12:32 PM
> Subject: [Disman] draft-ietf-disman-event-mib-v2-06.txt: Issue-1 -> "MAY not"
>

> Dear all,
>
> As pointed it out by Dave Shield in
> http://www1.ietf.org/mail-archive/web/disman/current/msg00648.html, one
> of the remaining issues in the draft is:
>
> Another question:
>    In a couple of places in this draft (mteObjectEntryStatus,
> mteEventEntryStatus, etc), the description refers to the term
> "MAY not".  What does this actually mean?
>
> RFC 2119 defines "MAY" as referring to optional features,
> and makes no mention of "MAY not".  Is this intended to be
> a prohibition on making any changes to an active row?
>
> If so:
>   a)  Shouldn't the text use  "MUST NOT" ?
>   b)  What's the purpose of the mteEventEnabled column
>         if the value can't be changed?
>   c)  What is the reason for this prohibition?
>
> Specifically, we speak about:
>
> mteObjectsEntryStatus OBJECT-TYPE
>     SYNTAX      RowStatus
>     MAX-ACCESS  read-create
>     STATUS      current
>     DESCRIPTION
>         "The control that allows creation and deletion of entries.
>         Once made active an entry MAY not be modified except to
>         delete it."
>     ::= { mteObjectsEntry 5 }
>
> mteEventEntryStatus OBJECT-TYPE
>     SYNTAX      RowStatus
>     MAX-ACCESS  read-create
>     STATUS      current
>     DESCRIPTION
>         "The control that allows creation and deletion of entries.
>         Once made active an entry MAY not be modified except to
>         modify the value of mteEventEnabled or to delete the entry."
>     ::= { mteEventEntry 5 }
>
> I share Dave's concern. It seems to me that MUST NOT is more appropriate in those two cases.
>
> Feedback?

Depending on what the WG would like the DESCRIPTION to mean,
let me suggest one of the two following for mteObjectsEntryStatus.
What implementations currently do could help us choose.

   This object allows creation and deletion of entries.
   When its value is 'active', attempts to set this object to any
   value other than 'destroy' MUST be rejected.  Likewise, attempts
   to set any of the of the other object instances in an active row
   MUST be rejected.

--or--

   This object allows creation and deletion of entries.
   When its value is 'active', implementations MAY reject requests
   to set this object to any value other than 'destroy'.  Likewise,
   implementations MAY reject requests to set any of the other
   object instances in an active row.

I would hope that the changes to mteEventEntryStatus would be similar.
My guess is that the first one was probably what was intended.
In both cases, note these requirements from the mib review guidelines:

     - The DESCRIPTION clause of the status column MUST specify which
       columnar objects (if any) have to be set to valid values before
       the row can be activated.  If any objects in cascading tables
       have to be populated with related data before the row can be
       activated, then this MUST also be specified.

     - The DESCRIPTION clause of the status column MUST specify whether
       or not it is possible to modify other columns in the same
       conceptual row when the status value is active(1).  Note that in
       many cases it will be possible to modify some writeable columns
       when the row is active but not others.  In such cases the
       DESCRIPTION clause for each writeable column SHOULD state whether
       or not that column can be modified when the row is active, and
       the DESCRIPTION clause for the status column SHOULD state that
       modifiability of other columns when the status value is active(1)
       is specified in the DESCRIPTION clauses for those columns (rather
       than listing the modifiable columns individually).

   - For conceptual rows that include a StorageType column:

     - The DESCRIPTION clause of the StorageType column MUST specify
       which read-write or read-create columnar objects in permanent(4)
       rows an agent must, at a minimum, allow to be writable.

Randy