Re: Tidying up DDL1 (last time?)

[Matthew Towler <towler@xxxxxxxxxxxxxx>]

> I don't think I see how
> supporting two different versions of DDL 1 would be any more difficult
> than supporting both DDL 1 and DDL 2; could you expand on that?  Any way
> around, I would expect most new software to support just the
> (hypothetical) DDL 1.5, not both 1.4 (or earlier) and 1.5.

The sentence following your question and the quote below make my 
comments rather redundant.  As long as a hypothetical DDL 1.5 did not 
make the vast majority of existing DDL 1.4 CIFs invalid then there is 
not a problem and programs could be updated as you suggest. I had 
misunderstood that 1.4 and 1.5 would be incompatible in some way.

> It is also desirable that any DDL changes should
> not ... render
> CIFs invalid that are valid under the dictionaries as they stand today.
> very many of the CIFs written against the [current]
> core dictionary are *not* valid *because* of .. dictionary and
> DDL flaws ... it may be that the proposed changes will be able to make many of
> these currently-invalid CIFs valid against the revised dictionary / DDL
> combination.

Thanks for the clarification

Matthew Towler


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