Index: branches/pyyaml3000/lib/yaml/resolver.py
===================================================================
--- branches/pyyaml3000/lib/yaml/resolver.py	(revision 55)
+++ branches/pyyaml3000/lib/yaml/resolver.py	(revision 56)
@@ -135,2 +135,9 @@
         ['='])
 
+# The following detector is only for documentation purposes. It cannot work
+# because plain scalars cannot start with '!', '&', or '*'.
+Resolver.add_detector(
+        u'tag:yaml.org,2002:yaml',
+        re.compile(ur'^(?:!|&|\*)$'),
+        list(u'!&*'))
+