src/Pure/PIDE/markup.scala

--- a/src/Pure/PIDE/markup.scala	Sun Oct 05 15:05:26 2014 +0200
+++ b/src/Pure/PIDE/markup.scala	Sun Oct 05 16:05:17 2014 +0200
@@ -120,6 +120,11 @@
   val EXPRESSION = "expression"
 
 
+  /* citation */
+
+  val CITATION = "citation"
+
+
   /* embedded languages */
 
   val Symbols = new Properties.Boolean("symbols")