[Standards] Duplicate feature in XEP-0060 (pubsub)

[Adrien]

Hi,

I am looking at the XEP-0060 and can't see the difference between 
"delete-items" et "retract-items"... is there any? It looks like a 
duplicate in the features, both entries link the same section, one is 
RECOMMANDED and the other OPTIONAL... If I have to choose, which one 
should I use?

http://xmpp.org/extensions/xep-0060.html#features
http://xmpp.org/extensions/xep-0060.html#publisher-delete

Thanks,
Adrien