Describes CIF, the data exchange standard of crystallography. Provides: information for scientists who wish to record or use the results of a single-crystal or powder diffraction experiment; the data ontology necessary for designing interoperable computer applications; accompanying software including machine-readable CIF dictionaries, libraries and utility programs.
An essential guide and reference to CIF for programmers, data managers handling crystal-structure information and practising crystallographers.
The number of reflections in the _refln_ list (not the _diffrn_refln_ list) that are significantly intense, satisfying the criterion specified by _reflns_threshold_expression. This may include Friedel-equivalent reflections (i.e. those which are symmetry-equivalent under the Laue symmetry but inequivalent under the crystal class) according to the nature of the structure and the procedures used. Special characteristics of the reflections included in the _refln_ list should be given in the item _reflns_special_details.
Related item: _reflns_number_observed (alternate)