This aims to provide a comma seperate list of the attributes/elements that pdbx_vrpt_software supplied.
The list is in an arbitrary order that can vary.
Example: classification="mogul_rmsz_numangles,mogul_angles_rmsz,mogul-torsion-outlier,mogul-angle-outlier,mogul-bond-outlier,mogul_bonds_rmsz,mogul-ring-outlier,mogul_rmsz_numbonds".
Note that the cross-referencing is not currently consistent as names can vary for instance
classification list includes "mogul-angle-outlier" but the attribute is "mog-angle-outlier".