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Re: Specifying values 'less than something' in CIFs?

Sounds like a good way to "park" the problem, pending a more general
future solution.  Formally, until the new tag is approved, you should use
a prefix.

On 4/29/12 8:25 AM, Saulius Grazulis wrote:
> Dear Herbert,
> many thanks for the answer!
> On 04/29/2012 02:57 PM, Herbert J. Bernstein wrote:
>> 0.001 is a number.<0.001 is a statement about a range
>> of numbers.  In CIF at the moment, there is already
>> a notation for some ranges of numbers, 0.0005(5), for
>> example, meaning 0.0005+/-0.0005, which may or may not
>> be intended to convey the same information as<0.001.
>> mmCIF deals with this complexity by explicitly making
>> _esd tags.
>> The issue needs to be dealt with in database searches.
>> Should a search for .0004 be satisfied by data given
>> as 0.0005(5)?  Most people would agree.  Should a
>> search for .0004 be satisfied by data given as<0.001?
>> Many people would be less certain.   Perhaps it is time to
>> revisit these conventions and settle on some extensions to the
>> notation to make life easier for users in preserving essential
>> metadata compactly while preserving the searchability of data
>> that includes that metadata.
> I agree with both of you comments. So, if I understand you correctly,
> specifying _refine_ls_shift/su_mean<0.001 in a DDL1 CIF should be
> correctly done as
> _refine_ls_shift/su_mean_lt 0.001
> This is easy to do, and easy to fix automatically.
> Regards,
> Salius

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