_Software_applied_history.Sf_ID, MS_chromatogram_list.Sf_ID, _MZ_ratio_data_list.Sf_ID, _Other_constraint_list.Sf_ID, _SAXS_constraint_list.Sf_ID, _Peak_constraint_link_list.Sf_ID, and more have empty parent/child

[epeisach]

Other ones include:
_H_chem_shift_constraint_list.Sf_ID
_CA_CB_constraint_list.Sf_ID
_J_three_bond_constraint_list.Sf_ID
_RDC_constraint_list.Sf_ID
_Torsion_angle_constraint_list.Sf_ID
_Floating_chirality_assign.Sf_ID

and more

If there is no parent/child, it should probably be removed from the dictionary definition.

loop_
_item_linked.child_name
_item_linked.parent_name

? ?

[elulrich]

This is correct and need to not write out these loops if they are empty