diff --git a/cif_core.dic b/cif_core.dic
index 7cea065..40e9eab 100644
--- a/cif_core.dic
+++ b/cif_core.dic
@@ -21752,7 +21752,7 @@ save_atom_site.u_iso_or_equiv_su
          '_atom_site_U_iso_or_equiv_su'
          '_atom_site.U_iso_or_equiv_esd'
 
-    _definition.update            2012-11-20
+    _definition.update            2023-06-25
     _description.text
 ;
     Standard uncertainty values (esds) of the U(iso) or U(equiv).
@@ -21761,7 +21761,7 @@ save_atom_site.u_iso_or_equiv_su
     _name.object_id               U_iso_or_equiv_su
     _name.linked_item_id          '_atom_site.U_iso_or_equiv'
     _type.purpose                 SU
-    _type.source                  Related
+    _type.source                  Derived
     _type.container               Single
     _type.contents                Real
     _units.code                   angstrom_squared