dw* types that use ISO class codes in specs now use \classcode macro

dfn/ins.tex

@@ -83,7 +83,7 @@ apply.
       \isoclassdef 68604 Vacant factory building.
       \isoclassdef 68606 Vacant non-factory building that is \emph{not} owned
                          by a not-for-profit company.
-      \isoclassdef 60607 Vacant non-factory building that \emph{is} owned by a
+      \isoclassdef 68607 Vacant non-factory building that \emph{is} owned by a
                          not-for-profit company.
     \end{description}