Subject: [Fax] Comments on ietf-fax-feature-schema-04.txt

From: James Rafferty <[email-masked]>
Date: Tue, 29 Dec 1998 11:31:53 -0500

Dear Graham, Lloyd,

Here are some editorial comments on the draft.   It appears to
me as if it is in great shape; the main area that needs some editorial
work is on the feature tag registations as noted below.

1.2
Terminology and document conventions

The term "eifax system" is used to describe any
software, device or

combination of these that conforms to the specification
"Extended

Facsimile Using Internet Mail" [5].

Since the term "eifax" will disappear when the RFC is
published, I think the term "extended Internet fax" would be
more readable.

3.7 Image
coding

Feature tag name    Legal values

----------------    ------------

image-file-
TIFF-S

structure
TIFF-F

TIFF-J

TIFF-C

TIFF-L

TIFF-M

(may be extended by further registrations,

to cover non-TIFF image file structures)

image-coding        MH

MR

MMR

JBIG

JPEG

(may be extended by further registrations)

image-coding-
JBIG-T85    (bi-level, per ITU T.85)

constraint
JBIG-T43    (multi-level, per ITU T.43)

JPEG-T4E    (per ITU T.4, Annex E)

(may be extended by further registrations)

JBIG-stripe-size    <Integer>

image-interleave    Stripe

Plane

color-subsampling
"1:1:1"     (no color subsampling)

"4:1:1"     (4:1:1 color subsampling)

MRC-mode
<Integer> (0..7)   (per ITU T.44 [15])

MRC-max-stripe-size <Integer>

There are quite a few options here and not too much guidance on how to
use them.   Should we include some kind of text in this section
which provides a small amount of guidance and a pointer to the examples
such as:

"For most applications, specification of the image-file-structure
tag and its values alone does not provide sufficient granularity to
precisely describe the image coding capabilities of a
recipient.   Implementors should provide sufficient
detail

so that it is clear values of these feature tags are supported and which
are not.  (See examples in section 4.)"

6. Full copyright statement

Copyright (C) The Internet Society 1998.  All Rights
Reserved.

We will now be in 1999.

8. References

For the informative references that will not yet be RFCs, we will have to
have some interaction with the RFC editor function.   This
could result in either retention or deletion of some informative
references so that the document is not held back.

Appendix A: Feature registrations

I suggested we change this title to:

"IANA Considerations - Feature Tag registations"

In order to fulfill the requirements of RFC 2434 to have a clear policy on the creation of new items within the IETF name space, as well as , I believe a simple preface can suffice, since I believe most of the relevant information is already defined in the media-feature-reg draft (your reference [1].

I would suggest a preface along these lines:

"The change control process for media feature tags is described in [1].   In this appendix, registrations of tags and values are provided which are intended to be part of the "IETF" registration tree as defined in section 3.1.1 of [1].  The proposals for these tags are subject to the "IETF Consensus" policies described in [RFC 2434].   The tag registrations as initially defined here have been reviewed within the Internet fax working group.   Each tag includes reference to a change controller; the IESG may elect at a future date to appoint a designated expert to fulfill the change control function or delegate this process to an active IETF working group.  The relevant mailing list for review of any changes at this time is "[email-masked]"."

A.1 Image size

-  Media Feature tag name(s):

size-x

size-y

-  ASN.1 identifiers associated with these feature tags:

[[[New assignments by IANA]]]

-  Summary of the media features indicated:

These feature tags indicate the size of a displayed, printed

or otherwise rendered document image;  they indicate

horizontal (size-x) and vertical (size-y) dimensions.

<snip>

-  Author/Change controller:

IETF (Fax Working Group)
A specific contact person with address information is needed here and for all of the feature tag registrations as part of the IANA considerations.  RFC 2434 talks about a designated expert appointed by the IESG AND that a relevant mailing list is useful.  In the suggested preface, I made reference to the ietf-fax list (which is likely to live longer than the Fax WG itself).     (we can discuss the best way to handle this with Keith).

Regards,

James

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James
Rafferty

President, Human Communications

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