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DDL1-DDL2

• Subject: DDL1-DDL2
• From: James Hester <jrh@xxxxxxxxxxxx>
• Date: Fri, 15 Jul 2005 17:32:32 +0900
• In-Reply-To: <42D6842B.7020608@ccdc.cam.ac.uk>
• References: <E88024C0BA8052478C717D472F978C1803251E44@iu-mssg-mbx05.exchange.iu.edu><42D6842B.7020608@ccdc.cam.ac.uk>

On Thu, 2005-07-14 at 16:26 +0100, Matthew Towler wrote:
> 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.

Yes, I think John expressed the situation very clearly, and I think of
the changes that have been suggested as janitorial work rather than
trying to enhance DDL1.  

You mentioned the relationship between DDL1 and DDL2.  Standing where I
am (largely unaware of the technical considerations that went into the
DDL2 design decisions) it appears that the DDL2 authors did 2 things;
they "cleaned up" DDL1, and they enhanced it (In the latter category I'm
thinking particularly of the way parent-child relationships are
expressed in DDL2, and the use of implicit attributes).  If DDL1 were to
adopt some of the DDL2 cleanups it would still (fortunately or
unfortunately) be a long way from being DDL2, but be a more robust
standard.

James. 
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• References:
  • RE: Tidying up DDL1 (last time?) (Bollinger, John Clayton)
  • Re: Tidying up DDL1 (last time?) (Matthew Towler)

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