src/Pure/General/position.ML

     val count =
       (case get_int props Markup.lineN of
         NONE => NONE
       | SOME m => SOME (m, the_default 1 (get_int props Markup.columnN)));
     fun property name = the_list (find_first (fn (x: string, _) => x = name) props);
-  in (Pos (count, property Markup.fileN @ property Markup.idN)) end;
+  in Pos (count, maps property Markup.position_properties') end;
 
 fun properties_of (Pos (count, props)) =
   (case count of
     NONE => []
   | SOME (m, n) => [(Markup.lineN, string_of_int m), (Markup.columnN, string_of_int n)]) @ props;