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Re: first post - question about file format

  • Subject: Re: first post - question about file format
  • From: James Hester <jamesrhester@xxxxxxxxx>
  • Date: Fri, 2 Dec 2016 11:26:30 +1100
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Hi Bob,

The magCIF dictionary does define a few datanames that use CIF2 vector syntax (datavalues enclosed by square brackets), and the square bracket at the start of a dataname is indeed not allowed in CIF1 format. The first characters of the file that you are reading in should state that it is CIF2.0 syntax ("#\#CIF_2.0") if it uses this square bracket syntax. The exclusion of square bracket at the start of a CIF1 data value is briefly discussed on p26 of VolG, section paragraph 11. (link http://it.iucr.org/Ga/ch2o2v0001/sec2o2o7/)

There is some CIF2 information at cif2.iucr.org, and the recent CIF2 paper is pretty comprehensive (https://doi.org/10.1107/S1600576715021871).  Note that the paper following the CIF2 paper describes a robust C library that reads both CIF1 and CIF2 syntaxes, which is perhaps not so useful for Java but might be useful to others reading this list.

I'm keen to hear any feedback on what resources for CIF2 are needed, so feel free to comment here or privately.

all the best,

On 2 December 2016 at 10:32, Robert Hanson <hansonr@stolaf.edu> wrote:
When upgrading Jmol to handle the new magCIF format, I spotted something I was not expecting - a syntax that broke Jmol's CIF reader:

  k1 [-0.75 0.75 -0.75]

To all accounts, this looks to me like CIF 2.0 format.

I'm pretty sure I saw in the CIF 1.0 specs that "[" at the beginning of an unquoted string is reserved -- I suppose just for this -- but I can't seem to find where this would be in the specs.

Can someone explain?

Bob Hanson

Robert M. Hanson
Larson-Anderson Professor of Chemistry
St. Olaf College
Northfield, MN

If nature does not answer first what we want,
it is better to take what answer we get.

-- Josiah Willard Gibbs, Lecture XXX, Monday, February 5, 1900

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