subscription namespace

The current documentation makes mention of a "special" subscription namespace. The example given:

namespace subscriptions { subscriptions = yes prefix = "" list = no hidden = yes }

namespace inbox { inbox = yes location = subscriptions = no [...]

results in a startup error as both namespaces have the same prefix. Was the intent for the "inbox" namespace to have an explicit "INBOX/" prefix?

If this is configured for an existing server that previously had no such "INBOX/" prefix namespace - will clients need to be reconfigured?

-- Daniel