- What happens when a node creation request is accompanied by a configure
  node, but node configuration is not implemented?

  Solution:

  Reply with a not-acceptable stanza error, with a node-not-configurable
  error attached.

- Node purging with many items in storage and notification of retraction enabled
could produce a large number of notifications. Suggestion: instead send a
<event><purge/></event>

- Examples 58 and 62 are the same

- What error to return for outcast user requests?
  - What if some admin requested it?

- Why not return forbidden when JIDs do not match on subscription?

- What to do when receiving an unsubscription request with a subid, when
  subids are not supported? Ignore or reply with bad-request?

- unsubscription: why check for the requestor being subscribed. You want to
  check if the jid is subscribed. An not-authorized can be sent if the
  requestor and jid don't match. Otherwise, unexpected-request might
  be appropriate when the jid is not subscribed along with a special
  child element of not-subscribed in the pubsub#error namespace.