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Differences between versions 2.0.x and 1.0 of the Core CIF Dictionary

Contents

Syntax
Dictionary formalism
Dictionary contents
Data files

Syntax

Dictionary formalism

CIF dictionaries are themselves STAR data files, with data blocks or save frames containing the definition and properties of the data names described. These definitions and properties are recorded with the use of data names described in a Dictionary Definition Language (DDL). Version 2.0 of the Core CIF dictionary employs a DDL different from that used in release 1.0. Consequently the layout of definition entries in the two dictionaries differs. For more information on DDL, consult the
DDL page on this server.

The major differences apparent to the average user are:

Dictionary contents

Considerable effort has been expended in ensuring compatibility with data names in old data files. To this end, version 2.0 of the Core dictionary includes all data names in version 1.0, with the following minor exceptions (both discussed further in the
Dictionary formalism section above):
  1. Names generated by the addition of suffixes listed as _units_extension in version 1.0. These may still be accessed through the compatibility CIF dictionary described above, but should not be used in new data files.
  2. _chemical_formula_appendix, which included a textual description of a group of data names and is replaced in version 2.0 by data names in the category_overview category.
In addition, the following data names, though still present in the version 2.0 dictionary, carry an indication that they should be replaced in future data files by alternative names. The purpose of this to align data names with the name structure of their parent category (i.e. it is potentially confusing that the data name _diffrn_radiation_detector should belong to the diffrn_detector category and not the diffrn_radiation one).
  1. _diffrn_radiation_detector should be replaced by _diffrn_detector
  2. _diffrn_radiation_detector_dtime should be replaced by _diffrn_detector_dtime
  3. _diffrn_radiation_source should be replaced by _diffrn_source
The following 203 data names are new in version 2.0 of the Core. They represent 55 category descriptions and 148 `real' data names. (The total number of data names defined in version 2.0 is 624.)

Data files

Every effort has been made to ensure that existing data files remain conformant to the new dictionary. Provided an existing CIF output application does not use derivative data names indicating the use of different physical units. as permitted in the original Core, the resultant files will fully conform to the Core CIF version 2.0 and upwards.

However, any data files wishing to use the new data names introduced in version 2.0 and later should include a record of the version of the dictionary against which the file was compiled. This is achieved by adding to each data block the pair of entries indicated below for the most recent version:

          _audit_conform_dict_name         cif_core.dic
          _audit_conform_dict_version      2.0.1

This will become increasingly important as dictionary validation software is written that checks data types, value ranges and interdependencies.


Updated 29 January 1997

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