diff -r d43e5f79bdc2 -r 834de29572d5 src/Pure/General/yxml.scala
--- a/src/Pure/General/yxml.scala	Tue Jul 12 19:47:40 2011 +0200
+++ b/src/Pure/General/yxml.scala	Tue Jul 12 19:49:35 2011 +0200
@@ -19,6 +19,8 @@
   val X_string = X.toString
   val Y_string = Y.toString
 
+  def detect(s: String): Boolean = s.exists(c => c == X || c == Y)
+
 
   /* string representation */  // FIXME byte array version with pseudo-utf-8 (!?)