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Re: [ddlm-group] A modest addition to the DDLm spec. .

This in fact is not a DDLm issue. It is a STAR and CIF syntax issue. The
broken regex example represents 3 separate data values to a single data name
with no loop construct to protect it - hence it violates the very basis of
the syntactic structure of both CIF and STAR. Apart from that it is fine!

You cannot parse these strings unambiguously unless you have a context that
says a data value that follows a _item_type_list.construct is completely
different to every other syntactic construct. I do not think that would not
be a wise variation to CIF2.

The triple quote solution suggested by John is the most sensible approach,
if the semi-colon delimited text is unfavoured.

Nick.


On 30/09/10 11:39 PM, "Bollinger, John C" <John.Bollinger@STJUDE.ORG> wrote:

> On Thursday, September 30, 2010 10:18 AM, SIMON WESTRIP wrote:
> 
>> First thought is how does this work in loops?
>> 
>> loop_ _item
>> 'abc' + 'def'
> 
> One specific (but synthetic) example I was thinking of was along the same
> lines:
> 
> loop_
>  _amino_acid.code
>  _amino_acid.optical_rotation_direction
>  'ALA' +
>  'ARG' +
>  'LEU' -
> 
>> But I need to check whether + is one of the characters that is not allowed to
>> start a
>> non-delimited string...
> 
> It is not.  Those are " ' _ $ [ {
> If the proposal is adopted then adding + to that list would reduce the added
> complications for parsing.  That would be incompatible with using the optional
> leading + with numeric values, however.
> 
>> Otherwise I see no reason not to explore this.
> 
> I see no reason at all not to explore it.  Notwithstanding the above, I have
> not yet formed an opinion on this question.
> 
> 
> Regards,
> 
> John
> --
> John C. Bollinger, Ph.D.
> Department of Structural Biology
> St. Jude Children's Research Hospital
> 
> 
> Email Disclaimer:  www.stjude.org/emaildisclaimer
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cheers

Nick

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