Subject: Re: I-D ACTION:draft-ietf-fax-feature-schema-03.txt

From: Graham Klyne <[email-masked]>
Date: Tue, 24 Nov 1998 11:45:01 +0000

Tamura-san,

Thank you for your question.  I do think this is a matter which would
usefully be clarified.

If I understand you correctly, you are asking if it is necessary to include
default capabilities in an Internet fax capability expression.

The short answer is, I believe:  this is not necessary, but it is desirable.

I try to explain below my reasons for this view:

The fax feature schema is a profile of a general capability feature
description scheme, and simply provides a means to describe media handling
capabilities that are provided by an application.  The capability
description framework does not have any concept of "default" capabilities:

+ if any feature is not explicitly mentioned in a capability description
option, then it is not constrained by that option.

+ if a feature is mentioned in a capability description option, then any
alowed values must be mentioned explicitly.

There are two possible cases to consider:
(A) a system with *only* minimum capabilities:  should it provide any
capability description?
(B) a system with greater than minimum capabilities:  assuming it provides
a capability description, should it include the TIFF-S capability in that
description?

(A) One of the recommendations of the "extended internet fax" specification
is that that minimum capabilities (TIFF-S) be advertised, even though they
are required for any Internet fax implementation, because by explictly
advertising this capability it shows the system is capable of "full mode"
behaviour as well as "simple mode".

(B) The presence or absence of any capabilities that are not allowed by a
capability description is, in my view, controlled by the "extended internat
fax" specification.  My interpretation is that TIFF-S would be allowed even
if not specifically mentioned in the capability desription provided.

However, I would recommend that the TIFF-S capability be mentioned
explictly, because this may ease interoperability with other applications
in the future.  This applies to both case (A) and (B).

#g

At 17:40 24/11/98 +0900, Hiroshi Tamura wrote:
>Klyne-san,
>McIntyre-san,
>
>Question.
>Does it have the defaultable system about the parameter ?
>
>For example, all must support Tiff-S capabilities.
>
>When capabilities are shown, conveyed or exchanged,
>the exchange or the identification of the capabilities
>beyond Tiff-S makes sense, but that of TIFF-S is not
>necessary or meaningless.
>
>Does it already cover ? If so, excuse me.
>Or other draft-RFC cover ?

------------
Graham Klyne
([email-masked])

---

From: Hiroshi Tamura <[email-masked]>
Date: Wed, 25 Nov 1998 17:49:30 +0900

Klyne-san,

Thank you for your reply.

>> Thank you for your question.  I do think this is a matter which would

I think so, too.

>> in the future.  This applies to both case (A) and (B).

Other applications are NOT internet fax application. Right ?
I almost understand.

Anyway, it is better to clarify.

--
Hiroshi Tamura, Ricoh Company, LTD.
Mail: [email-masked]
Tel: +81-462-28-7459  Fax: +81-462-28-7500 (SUB/F-code 5727)