src/Pure/PIDE/command.scala

                         else if (chunk_name == Symbol.Text_Chunk.Default)
                           other_id(command.node_name, id)
                         else None
 
                       (target, target_range) match {
-                        case (Some((target_name, target_chunk)), Some(symbol_range)) =>
+                        case (Some((target_name, target_chunk)), Some(symbol_range))
+                        if !symbol_range.is_singularity =>
                           target_chunk.incorporate(symbol_range) match {
                             case Some(range) =>
                               val props = atts.filterNot(Markup.position_property)
                               val elem = xml_cache.elem(XML.Elem(Markup(name, props), args))
                               state.add_markup(false, target_name, Text.Info(range, elem))