How to configure subscriber's subscription

How is it possible to get subscriber’s options like described in here:

http://xmpp.org/extensions/xep-0060.html#subscriber-configure

I tried this:

<pubsub xmlns='[http://jabber.org/protocol/pubsub](http://jabber.org/protocol/pubsub)'>   

<field var='FORM_TYPE' type='hidden'><value>[http://jabber.org/protocol/pubsub#subscribe_options](http://jabber.org/protocol/pubsub#subscribe_options)</value></field>                  

2

However, this doesn’t seem to work…