diff -r ceb190f4f69f -r 301a721af68b src/Pure/PIDE/protocol.scala
--- a/src/Pure/PIDE/protocol.scala	Fri Nov 22 20:54:26 2013 +0100
+++ b/src/Pure/PIDE/protocol.scala	Fri Nov 22 21:13:44 2013 +0100
@@ -352,8 +352,6 @@
       def encode_edit(name: Document.Node.Name)
           : T[Document.Node.Edit[Command.Edit, Command.Perspective]] =
         variant(List(
-          // FIXME Document.Node.Blob (!??)
-          { case Document.Node.Clear() => (Nil, Nil) },  // FIXME unused !?
           { case Document.Node.Edits(a) => (Nil, list(pair(option(id), option(id)))(a)) },
           { case Document.Node.Deps(header) =>
               val master_dir = Isabelle_System.posix_path(name.master_dir)