Release Notes for CIF CORE 3.2.0

What's New: CIF Core 3.2.0

The following changes are relative to 3.0.13, which was the last released version (June 2020). Only the most significant changes are detailed below; the full list of changes is available here.

New capabilities

Author lists

Authors should now be identified by an opaque identifier, instead of relying on a unique first name, last name combination. See the AUDIT_AUTHOR and PUBL_AUTHOR categories. Authors of software that writes CIF files may add _audit_author.id and _publ_author.id to their output without risking breakage of legacy software.

Author roles

The role that an author played in the experiment can now be specified using the list provided in _audit_author_role.role. The current list is:

        design              'conceived and/or designed the experiment'
        synthesis           'synthesised the samples'
        preparation
;
              prepared the samples for measurement, e.g. crystallised or 
              recrystallised the sample
;
        characterisation     'performed non-crystallographic measurements on the samples'
        measurement          'collected and/or reduced diffraction data'
        analysis             'worked on the structural model'
        software             'developed bespoke software for specialised data processing and/or analysis'
;
        submission           'prepared the final CIF file'

Research support

The AUDIT_AUTHOR_SUPPORT category has been added to allow description of the sources of support for the work reported in the data file. Sources of support include funding organisations and various awards.

Elemental composition

There is support for recording the elemental composition of the specimen through the addition of ATOM_ANALYTICAL, ATOM_ANALYTICAL_MASS_LOSS, and ATOM_ANALYTICAL_SOURCE.

An analyte element and its mass percent can be given, along with the type of the measurement. In some cases, such as XRF, results are given in terms of oxides. In this case, the relevent chemical species and species mass percent can be given, as well as mapped to the relevant analyte element. Furthermore, any mass results, such as through high-temperature treatment, can also be recorded. Lastly, the instrumentation used to collect the elemental composition results can be described.

Examples of its use can be found here, here, and here.

Multi-block data sets

As specified in this document, complex data may now be distributed over multiple data blocks. The Default way of distributing data, which is backwards-compatible, specifies that items in Set categories may only take one value per data block. If more than one data block will contain values from such Set categories, key data names must have been assigned in the dictionaries to those Set categories.

The DIFFRN category and related categories have now been equipped with a key data name (_diffrn.id) allowing experiments undertaken in varying environmental conditions to be expressed as a single, multi-block data set. Similarly, where data is measured from multiple crystals each crystal can be described separately using data names from the EXPTL_CRYSTAL category spread over multiple blocks.

Future releases will expand this multi-block capability to further categories.

Software that is unaware of such multi-block data sets should still function correctly when passed the contents of any single data block.

Cells measured under different conditions to the diffraction data

In the original CIF core, _cell_measurement.temperature and -_pressure were provided to allow for the unit cell measurement conditions to differ from those used for the data collection. These data names have now been deprecated. In the usual case that the cell was determined at the same time as the diffraction peaks, cell measurement conditions are indicated using _diffrn.ambient_temperature and _diffrn.ambient_pressure. In the rare case that the unit cell was measured under different conditions, _cell_measurement.condition_id should be set to the _diffrn.id of a data block containing the cell measurement conditions provided using _diffrn.ambient_temperature and _diffrn.ambient_pressure. See insert link to example for an example.

New data names

• _diffrn_source.beamline and _diffrn_source.facility
• _diffrn.crystal_id. An identifier for the crystal used to collect the diffraction data.
• _audit_author.id and _publ_author.id (see above).
• _audit_author_role.role and _audit_author_role.special_details (see above)
• _diffrn_refln.intensity_{bg_1, bg_2, net, peak, total} have been added to allow quantities that are not directly measured counts to be recorded. The _diffrn_refln.counts_* data names should only be used when the quantity recorded has a standard uncertainty determined by counting statistics.
• _exptl_absorpt.special_details for describing absorption corrections where other data names are not sufficient.
• data names for more detailed description of elemental compositions: see above.
• data names for detailing sources of support for the research: see above.
• _citation.URL and _journal_paper.URL
• _journal.paper_number and _journal.paper_pages
• _model_site.adp_eigenvectors and _model_site.adp_eigenvalues.

Deprecated data names

The following data names should no longer be used. If your software outputs them, you should update to their replacements. If your software reads them, it should be updated to also read the replacements.

• _diffrn_radiation.type and _diffrn_radiation.xray_symbol have been replaced by _diffrn_radiation_wavelength.type and _diffrn_radiation_wavelength.xray_symbol

• _cell_measurement.temperature, pressure etc... These should almost always be replaced by _diffrn.ambient_{temperature/pressure/etc.} See above for more details.

Removed data names

Normally, data names are never removed. The following data names were introduced with the original DDLm dictionaries, but never used in data files, so it was decided that it would be safe to remove them.

• _model_site.adp_eigen_system
• _citation_author.key
• _citation_editor.id

Minor improvements

• Updated author-related definitions to explain how single-name authors are handled.
• Fixed various references and URLs
• Clarified that _atom_site.disorder_assembly and -_group also apply to compositional disorder.

Fixes

• Corrected DIFFRN_STANDARD to DIFFRN_STANDARDS for consistency with DDL1 core dictionary