Content-Based Pubsub System

Hi everybody,

currently I’m using the topic-based subscription system of XMPP, where the clients subscribe to different nodes.

Additionally, I want to use a content-based subscription mechanism as sketched in XEP-0060, section 12.19.

The spec. does not define any details about it.

My question is, if content-based subscriptions are specified in another document?

Or if it is officially not supported by XMPP and I have to implement this on my own?

Thanks in advance,

Mike