src/Pure/Isar/keyword.ML

 fun lookup_command (Keywords {commands, ...}) = Symtab.lookup commands;
 
 fun command_markup keywords name =
   lookup_command keywords name
   |> Option.map (fn {pos, id, ...} =>
-      Position.make_entity_markup false id Markup.command_keywordN (name, pos));
+      Position.make_entity_markup {def = false} id Markup.command_keywordN (name, pos));
 
 fun command_kind keywords = Option.map #kind o lookup_command keywords;
 
 fun command_tags keywords name =
   (case lookup_command keywords name of