diff -r 5b2391321bab -r dc7455787a8e src/Pure/Concurrent/par_exn.ML
--- a/src/Pure/Concurrent/par_exn.ML	Thu Sep 21 17:09:48 2023 +0200
+++ b/src/Pure/Concurrent/par_exn.ML	Thu Sep 21 18:14:28 2023 +0200
@@ -7,8 +7,6 @@
 
 signature PAR_EXN =
 sig
-  val identify: Properties.T -> exn -> exn
-  val the_serial: exn -> int
   val make: exn list -> exn
   val dest: exn -> exn list option
   val is_interrupted: 'a Exn.result list -> bool
@@ -19,36 +17,19 @@
 structure Par_Exn: PAR_EXN =
 struct
 
-(* identification via serial numbers -- NOT portable! *)
-
-fun identify default_props exn =
-  let
-    val props = Exn_Properties.get exn;
-    val update_serial =
-      if Properties.defined props Markup.serialN then []
-      else [(Markup.serialN, serial_string ())];
-    val update_props = filter_out (Properties.defined props o #1) default_props;
-  in Exn_Properties.update (update_serial @ update_props) exn end;
-
-fun the_serial exn =
-  Value.parse_int (the (Properties.get (Exn_Properties.get exn) Markup.serialN));
-
-val exn_ord = rev_order o int_ord o apply2 the_serial;
-
-
 (* parallel exceptions *)
 
 exception Par_Exn of exn list;
-  (*non-empty list with unique identified elements sorted by exn_ord;
+  (*non-empty list with unique identified elements sorted by Exn_Properties.ord;
     no occurrences of Par_Exn or Exn.Interrupt*)
 
 fun par_exns (Par_Exn exns) = exns
-  | par_exns exn = if Exn.is_interrupt exn then [] else [identify [] exn];
+  | par_exns exn = if Exn.is_interrupt exn then [] else [Exn_Properties.identify [] exn];
 
 fun make exns =
   let
     val exnss = map par_exns exns;
-    val exns' = Ord_List.unions exn_ord exnss handle Option.Option => flat exnss;
+    val exns' = Ord_List.unions Exn_Properties.ord exnss handle Option.Option => flat exnss;
   in if null exns' then Exn.Interrupt else Par_Exn exns' end;
 
 fun dest (Par_Exn exns) = SOME exns