diff -r 46f59511b7bb -r d97fdabd9e2b src/HOL/IMP/Procs.thy
--- a/src/HOL/IMP/Procs.thy	Fri Sep 20 19:07:10 2024 +0200
+++ b/src/HOL/IMP/Procs.thy	Fri Sep 20 19:51:08 2024 +0200
@@ -8,12 +8,12 @@
 
 datatype
   com = SKIP 
-      | Assign vname aexp        ("_ ::= _" [1000, 61] 61)
-      | Seq    com  com          ("_;;/ _"  [60, 61] 60)
-      | If     bexp com com     ("(IF _/ THEN _/ ELSE _)"  [0, 0, 61] 61)
-      | While  bexp com         ("(WHILE _/ DO _)"  [0, 61] 61)
-      | Var    vname com        ("(1{VAR _;/ _})")
-      | Proc   pname com com    ("(1{PROC _ = _;/ _})")
+      | Assign vname aexp        (\<open>_ ::= _\<close> [1000, 61] 61)
+      | Seq    com  com          (\<open>_;;/ _\<close>  [60, 61] 60)
+      | If     bexp com com     (\<open>(IF _/ THEN _/ ELSE _)\<close>  [0, 0, 61] 61)
+      | While  bexp com         (\<open>(WHILE _/ DO _)\<close>  [0, 61] 61)
+      | Var    vname com        (\<open>(1{VAR _;/ _})\<close>)
+      | Proc   pname com com    (\<open>(1{PROC _ = _;/ _})\<close>)
       | CALL   pname
 
 definition "test_com =