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Release Notes for version 1.1.0
The multiblock dictionary provides definitions that allow datasets to be spread over multiple data blocks while maintaining well-defined relationships between data items in all data blocks. Below is a short summary of the main differences. A full list of all changes is available here.
The concept of a crystal structure is, of course, pervasive in CIF dictionaries, but there is no way to assign a structure to a data name, and neither is it made clear which data names contribute to the definition of a structure. Of course, as long as only a single structure is considered, there is no practical need to clarify at a formal level what is meant by 'structure', as the community understands the data names that are needed. However, as soon as a data item should refer to a structure (e.g. "the average structure", "the parent structure"), formal definition becomes necessary. The multiblock dictionary now includes a STRUCTURE category, which attaches an identifier to a structure using _structure.id, and distributes child key data names of this identifier to all LOOP categories involved in describing the structure. Other data names in the STRUCTURE category link to the space group and unit cell, and dictionaries that import the multiblock dictionary can add child key data names to those categories which provide further structural information, whether that be magnetic structure or modulated structure. A STRUCTURE as defined in the multiblock dictionary therefore consists at a minimum of the space group, unit cell, and atomic sites. Other categories that assume a particular structure include the GEOM_BOND, GEOM_CONTACT, and other GEOM_* categories.
As long as data blocks adhere to the default _audit.schema, it is sufficient to set the value of _structure.id in the data block, after which the values of all child key data names can be assumed and therefore elided. Where only one structure is presented, _structure.id can also be omitted.
Many categories in the core dictionary were implicitly connected via relating to the same experimental conditions during measurement. These categories have been provided with an explicit child data name (sometimes a key data name) of _diffrn.id.