Subject: Unspecified Properties, Defaults and Value Replacement

From: Tom-PT Taylor <[email-masked]>
Date: Wed, 19 Apr 2000 15:10:50 -0500

I have done some further thinking and research on the "unspecified value"
issue.  Here are my new thoughts.  I would very much welcome comments.

Section 6.2.4 presents a data model which is not an accurate representation
of subsequent parts of the protocol document.  There are several statements:
 -- most properties have default values
 -- when a termination is created, unspecified properties are given their
default values
 -- when a termination is modified, unspecified properties retain their
previous values.

As noted in a previous thread, a lot of our data behaviour is actually
specified at the descriptor level.  In addition, the sensible initial state
for most descriptors is either "no value" or "empty", although this could be
modified by provisioning for specific terminations.  Here's a complete list
of descriptors and the initial values I think we intend:

Descriptor              Initial Value When Termination Created
----------------
--------------------------------------------------------
Modem                  No value
Multiplex                No value

Media                    See components
TerminationState    ServiceStates=InService; EventBufferControl=Off
Stream                  See components
Local                     Empty
Remote                 Empty
LocalControl          Mode=inactive[?]; Reservexx=Off

Events                  Empty, RequestID=0[?]
EventBuffer            Empty
Signals                 Empty
Audit                    Empty
DigitMap               Empty

I propose that the above table be added to section 6.2.4 and and the text on
initial values for properties be modified to refer to the table instead
(with suitable reference to packages where applicable).  The question marks
for Mode and RequestID are because we do not actually specify those defaults
in our text.

The other point to be straightened out is the fact that descriptor-level
semantics are important.  I think the following are true statements of our
intent.  If so, sections 6.2.4 and 7.1.1 should be modified to reflect them:

 (1) When a specific descriptor is specified in a command, the contents of
that descriptor completely replace any previous settings of properties
within that descriptor.  THERE ARE THREE EXCEPTIONS: DigitMap does its
replacement at the level of the individual named digit map, and we probably
want unspecified properties in TerminationState and LocalControl to retain
their previous values.

 (2) If a specific descriptor is omitted from a command, its previous
contents are retained.

Tom Taylor
Phone and FAX: +1 613 736 0961
E-mail: [email-masked]

---

From: Christian Groves <[email-masked]>
Date: Thu, 27 Apr 2000 11:59:07 +1000

G'Day Tom,

Why do we want the exception for Local Control and Termination State in
(1) below?

Cheers, Christian