+=head2 OTHER CLASSES
+
+Perl 5.18 introduces a new class, B::PADLIST, returned by B::CV's
+C<PADLIST> method.
+
+=head2 B::PADLIST Methods
+
+=over 4
+
+=item MAX
+
+=item ARRAY
+
+A list of pads. The first one contains the names. These are currently
+B::AV objects, but that is likely to change in future versions.
+
+=item ARRAYelt
+
+Like C<ARRAY>, but takes an index as an argument to get only one element,
+rather than a list of all of them.
+
+=item REFCNT
+
+=back
+
+=head2 $B::overlay
+
+Although the optree is read-only, there is an overlay facility that allows
+you to override what values the various B::*OP methods return for a
+particular op. C<$B::overlay> should be set to reference a two-deep hash:
+indexed by OP address, then method name. Whenever a an op method is
+called, the value in the hash is returned if it exists. This facility is
+used by B::Deparse to "undo" some optimisations. For example:
+
+
+ local $B::overlay = {};
+ ...
+ if ($op->name eq "foo") {
+ $B::overlay->{$$op} = {
+ name => 'bar',
+ next => $op->next->next,
+ };
+ }
+ ...
+ $op->name # returns "bar"
+ $op->next # returns the next op but one
+