Question: What about cmi cross reference ids that not related?
SQL: SELECT cmi_cross_ref_id FROM cmi_cross_references where cmi_cross_ref_id not in  ( Select T1.cmi_cross_ref_id from cmi_cross_references as T1 join Parking_Fines as T2 on T1.cmi_cross_ref_id  =  T2.cmi_cross_ref_id )