Subject: IST/18 comments on NP on PREMO (fwd)

From: Chris Cartledge <[email-masked]>
Date: Tue, 30 Nov 1993 17:54:20 +0100

Colleagues,

I have discussed the matter with Steve Price (UK SC18) and in the absence
of other input (other than the earlier acceptance of the document with no
comment by UK SC24 experts) have jointly agreed the following: 

Title:	UK comments to JTC1 on NP on PREMO (Presentation Environments for 
Multimedia Objects)

Date	1993-11-30

(JTC1 N2627) : Revised text of a proposal for a New Work Item on 
Presentation Environments for Multimedia Objects (PREMO)

The UK votes YES to this NP and does not want to see technical work
postponed further.  However some UK experts have serious reservations
about the direction of the work and so the UK requests that the Working
Group address the following issues at an early date. 

In particular, in respect of ODA, the UK suggests that there be a joint
meeting of SC18 and SC24 experts to determine the suitability of ODA
(either itself or the concepts) as a storage and transfer mechanism for
PREMO.  There also need to be joint meetings to ensure that MHEG and 
PREMO experts can agree the relationship and interfaces between PREMO 
and MHEG.

The other comments are under three headings:

1. duplication of existing standards
2. support of existing standards
3. general structure of the proposed work

1. DUPLICATION OF EXISTING STANDARDS

The revised text of the NP does not adequately address the previously
raised issue of duplication of standard specifications.  The work of the
PREMO group must be directed so that that it builds upon existing
standards whereever possible rather than duplicating them as the current
text might suggest. 

ISO 8613 : 1989 (ODA) specifies the structuring and relationships of
multiple content types.  Importantly it also standardises the layout and
presentation of multiple contents in relationship with each other. 
ISO/IEC 8613-14, currently at the stage of DIS, adds provision for time
and hypermedia relationships.  The above is all defined in an object
oriented manner permitting access to and handling of individual and
composite objects.  The text of the NP would suggest that SC24 will be
re-invent these features under the PREMO work item.  Instead the issues 
need to be examined jointly with SC18 experts. 

ISO/IEC 135221-1 (MHEG), currently at the stage of DIS, specifies similar
structuring, layout and presentation facilities for a real-time
interchange environment.  The relationship between ODA and MHEG is clear
and a technical report on their interworking is in preparation.  Both ODA
and MHEG have been developed in collaboration with ITU-T.  Again SC24 
needs to agree a relationship with MHEG experts.

2. SUPPORT FOR EXISTING STANDARDS

The revised text does not demonstrate that the resulting work will fully
support existing standards.  The PREMO work must address the issue of
interfaces to support existing standards and not constrain itself to a
restricted set of applications. 

The added value aspect of PREMO is the specification of an interface to an 
environment in which all, many as yet unknown, data formats can be 
presented in relation to each other. In this regard the proposal is weak 
because it constrains itself to specific structures and models.  To quote 
from clause 2.2.7, "HyperODA and PREMO could achieve interoperability if 
HyperODA were specified as a HyTime application".  HyperODA (ISO/IEC DIS 
8613-14) is not a HyTime application, neither is MHEG and neither will be 
many other hypermedia data formats and consequently PREMO is not serving the 
needs of a wide range of applications.

3. GENERAL STRUCTURE OF THE PROPOSED WORK

The NP contains an open ended statement of extensions that will be
developed (see clause 2.2.1).  Each item of extension should be the
explicit subject of future NPs.