Description
I think there are a few examples of redundant information being included in the CIF examples
eg:
In this example, _structure.space_group_id and _structure.phase_id are explicitly given, even though there are already values of _space_group.id and _pd_phase.id given. AFAIK, values for data names that are links are "autopopulated" if the data name they link is present in the same block. For example, you don't explicitly give a value to _cell.structure_id, below.
data_CuCr2O4
_audit_dataset.id 6bdf3aa2-a2d9-41a3-ae76-36af9af8ab19
_structure.id CuCr2O4
_structure.space_group_id fddd
_structure.phase_id cucr2o4
_pd_phase.id cucr2o4
_pd_phase_mass.percent 98.7
_space_group.crystal_system orthorhombic
_space_group.id fddd
_space_group.laue_class mmm
_space_group.name_h-m_alt 'F d d d'
_space_group.name_Hall '-F 2uv 2vw'
#symops could go here
_cell.angle_alpha 90.0
_cell.angle_beta 90.0
_cell.angle_gamma 90.0
_cell.length_a 7.712
_cell.length_b 8.543
_cell.length_c 8.536
_cell.volume 562.481
loop_
_atom_site.label
_atom_site.type_symbol
_atom_site.fract_x
_atom_site.fract_y
_atom_site.fract_z
Cu Cu 0.125 0.125 0.125
Cr Cr 0.5 0.5 0.5
O O 0.2457 0.2682 0.2674
(I also just noticed an error with this inasmuch as you can't give _pd_phase_mass.percent without also defining _pd_diffractogram.id.
.
This next example is clean: the _pd_refln.phase_id, _pd_phase_mass.phase_id, _refln.diffractogram_id, and _pd_phase_mass.diffractogram_id values are taken from the values of _pd_phase.id and _pd_diffractogram.id given in the block.
data_0H_cr2cuo4
_audit_dataset.id c5c4b947-0708-411e-b44b-e157f645fd23
_pd_diffractogram.id 0H_00
_pd_phase.id cr2cuo4
_pd_phase_mass.percent 0.9888(4)
# The following assumes that _refln.diffractogram_id
# has been defined so that per-diffractogram results
# can be provided.
loop_
_refln.index_h
_refln.index_k
_refln.index_l
_refln.F_squared_meas
_refln.F_squared_calc
_refln.phase_calc
_refln.d_spacing
1 1 1 2923.7101 1848.8118 0.0 4.75465
0 2 2 50887.9824 44176.2312 180.0 3.01930
2 2 0 41129.5142 38146.8191 180.0 2.86244
2 0 2 40719.7976 38182.2594 180.0 2.86141
# ...
# preferred orientation information also goes here
I just want to check that this truly is redundant information, and you're not having them there explicityly for any teaching (or other) purposes, before I start removing them.
some links: