Hello everyone, There is a potential problem with some of the geometric properties of atoms in mmCIF, in that related values can possibly become 'uncoupled' from each other. For example, if a matrix is applied to the coordinates, the rotational part should also be applied to the standard deviations of the coordinates, and anisotropic temperature factors and their standard deviations. I think that there may be scope for defining a subcategory which could be used to group these items together. Regards, Peter.