=head1 DESCRIPTION
-memcached_delete() is used to delete a particular key. An expiration value
-can be applied so that the key is deleted after that many seconds, but this
-will only work if you are using a 1.2.x server. If you are using a 1.2.x
-server and you want to use the expiration value, please call memcached_version
-one time for the memcached_st instance. If you don't do this no-reply and
-buffered mode will be disabled to avoid getting out of sync with the server.
+memcached_delete() is used to delete a particular key.
memcached_delete_by_key() works the same, but it takes a master key to
find the given value.
+Expiration works by placing the item into a delete queue, which means that
+it won't possible to retrieve it by the "get" command, but "add" and
+"replace" command with this key will also fail (the "set" command will
+succeed, however). After the time passes, the item is finally deleted from server memory.
+
+Please note the the Danga memcached server removed support for expiration in
+the 1.4 version.
+
=head1 RETURN
A value of type C<memcached_return_t> is returned