[sc34wg3] Backwards Compatability

[Sam Hunting]

To the ISO list--

[lars]
> I think we all agree that since the purpose of the foundational model
> is to remove the ambiguities of those specifications, the removal of
> some of these ambiguities will cause behaviour that before seemed
> legal to now be illegal. This will be limited to minor issues of
> processing, however, and not involve any changes to the XTM 1.0
> model.

As for the purpose that "we" all agree on -- I've missed the part of
the ISO minutes where this is stated. I append what I think is the
relevant portion of the ISO minutes for your reference:

    Development of a Core (Level 0) Model that defines the essential 
    nature of topic maps at the lowest level and does not 
    distinguish between association types

    Development of an Infoset (Level 1) Model, defined in terms of the 
    Core Model (or with an unambiguous mapping to it), and additionally
    defining the semantics of topic-basename, basename-variantname, and
    topic-occurrence relationships.

As to models, the only "models" I know about that are relevant to the
ISO list are the "level 0" and "level 1" models. If there is a model in
XTM 1.0 it is either informative (the conceptual model and Annex F) or
implicit. Therefore, the phrase "changes to the XTM 1.0 model" assumes
precisely what is at issue -- that there is universal agreement on what
the XTM 1.0 model is. 

[lars]
> It seems to me self-evident that we cannot possibly fly the aircraft
> and rebuild it at the same time. 

If you accept that metaphor, which I don't. We CAN "drive over the
bridge while the workmen are painting it", or "avoid upsetting the
apple cart even if we are driving it over rough ground." The world is,
perhaps, not quite as binary as you suggest.

[lars]
> Either we must make it clear that topic maps are still up in the air
> and still under construction, so that nobody should use them for
> mission-critical purposes, or we must make it clear that topic maps
> are done, finalized for the foreseeable future, and ready for prime
> time.

Topic maps are not "up in the air", they are on the ground! (At least
in the metaphor I accept). And as such, changes are going to happen
topic maps -- maybe even to "the model"

It's very unclear to me, then, why ISO would initiate the level 0 and
level 1 work items if indeed topic maps are "finalized." 

[lars]
> As I see it, this need not be so difficult. We have a model that is
> accepted by the implementors (the infoset one), we have a model that
> is accepted by the editors of 13250 (PMTM4), and we have a WG3
> decision on how to proceed[2], which states that we should further
> develop both, and produce a mapping between them.

The infoset is accepted by "all" the implementors? I'm not so sure. 

S.

P.S. If people could stop referring to the XTM specification as a
"standard" (which implies that it has the same status as an ISO work
product) and if people could distinguish between the normative and
informative portions of the XTM 1.0 specification in discussion, the
clarity of our discussions would be greatly increased.



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