RE: Fwd: [xml-dev] Data versioning strategy: address semantic, re lationship, and syntactic changes?

Len Bullard writes:

> The problem then is may be multi-variate:  a change breaks one 
> system but not another.  As in does not break the processing 
> application but does break the help description of the running 
> system.  It isn't just *identifying* the change; it is capturing the
> real and non-real time effects.
> 
> That is the difference between *a* version (identifying the 
> resource) and version control (identifying and executing the 
> process).  Not a new topic here or elsewhere.

Yes, I agree.  More fundamentally, I think we need to be careful with 
terminology.  It's quite common to see discussions in which there is 
debate about whether version 1 of a language is compatible with version 2. 
 I don't think Roger's original note falls into that trap, but I think 
some of the discussion has tended in that direction.  The terminology we 
use can, unintentionally, frame the discussion in ways that hides 
important issues.  I think it's usually more appropriate to ask: "for what 
range of uses can document D authored to conform to the specification of 
version X of a language be safely usable if interpreted per the 
specification for version Y?" and "for what range of uses can >all 
documents< authored to conform to the specification of version X of a 
language be safely usable if interpreted per the specification for version 
Y?"  That latter question tends to capture what one means by language VX 
is/isn't compatible with language VY.  This is just my opinion, but I've 
found it a useful way to frame things.

Noah

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Noah Mendelsohn 
IBM Corporation
One Rogers Street
Cambridge, MA 02142
1-617-693-4036
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