+=item * I<File tests>
+
+ "-X"
+
+This overload is used for all the filetest operators (C<-f>, C<-x> and
+so on: see L<perlfunc/-X> for the full list). Even though these are
+unary operators, the method will be called with a second argument which
+is a single letter indicating which test was performed. Note that the
+overload key is the literal string C<"-X">: you can't provide separate
+overloads for the different tests.
+
+Calling an overloaded filetest operator does not affect the stat value
+associated with the special filehandle C<_>. It still refers to the
+result of the last C<stat>, C<lstat> or unoverloaded filetest.
+
+If not overloaded, these operators will fall back to the default
+behaviour even without C<< fallback => 1 >>. This means that if the
+object is a blessed glob or blessed IO ref it will be treated as a
+filehandle, otherwise string overloading will be invoked and the result
+treated as a filename.
+
+This overload was introduced in perl 5.12.
+
+=item * I<Matching>
+
+The key C<"~~"> allows you to override the smart matching logic used by
+the C<~~> operator and the switch construct (C<given>/C<when>). See
+L<perlsyn/switch> and L<feature>.
+
+Unusually, overloading of the smart match operator does not automatically
+take precedence over normal smart match behaviour. In particular, in the
+following code:
+
+ package Foo;
+ use overload '~~' => 'match';
+
+ my $obj = Foo->new();
+ $obj ~~ [ 1,2,3 ];
+
+the smart match does I<not> invoke the method call like this:
+
+ $obj->match([1,2,3],0);
+
+rather, the smart match distributive rule takes precedence, so $obj is
+smart matched against each array element in turn until a match is found,
+so you may see between one and three of these calls instead:
+
+ $obj->match(1,0);
+ $obj->match(2,0);
+ $obj->match(3,0);
+
+Consult the match table in L<perlsyn/"Smart matching in detail"> for
+details of when overloading is invoked.
+