ImgCIF

ImgCIF is the official specification for the .cbf format (not minicbf).

While this may not be something we should copy, it might be useful to compare what we are coming up with to existing formats, like this one.

The official page seems to be here, but that is apparently quite out of date. The newest version seems to be 1.8.8 (this one), and version 1.8.6 is on github. The file contains some very good lists of all attributes for each category, and documentation for the category (top of file).

There are diagrams of the individual categories, and which are used in actual depositions here.

The file below shows an approximate UML diagram of ImgCIF (omitting a few less relevant classes), made by rhfogh. ImgCIF.drawio.pdf

Links are either composition ('part of', filled diamond), or mandatory one-to-many links. Only key and foreign-key attributes are shown.

It is hard to be completely precise here. The two classes in in CAPITALS (ArrayStructureSection and AxisSet) do not correspond to an existing category, but match a group of child objects, with no additional attributes (e.g. AxisSet is a grouping of ARRAY_STRUCTURE_LIST_AXIS), The DifractionDataSet category seems to be a placeholder for the equivalent category in mmCIF. It obviously corresponds to an entire data set (which would then contain Scans etc.) but the relevant links are not fully modelled. Also the DIFFRN_RADIATION_WAVELENGTH class is not listed in the ImgCIF document, but is part of mmCIF; on the other hand DIFFFRN_RADIATION has a wavelength_id but no wavelength value, so something is obviously needed here.