diff -r a24865b6262f -r 9efccbad7d42 src/Pure/PIDE/xml.scala
--- a/src/Pure/PIDE/xml.scala	Wed Feb 13 11:25:23 2019 +0100
+++ b/src/Pure/PIDE/xml.scala	Thu Feb 14 14:44:41 2019 +0100
@@ -99,6 +99,8 @@
 
   /** string representation **/
 
+  val header: String = "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n"
+
   def output_char(c: Char, s: StringBuilder)
   {
     c match {