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$Id: rdataset,v 1.6 2004/03/05 05:04:46 marka Exp $

Need way to "dup" an rdataset (i.e. different rdataset handle, same underlying
data).

DB addnode routine should take an rdataset *, which, if non-NULL, would be
attached to the added rdataset.

Need credibility, security status.

Cache security status in rdataset.  Have rdataset supply methods to get/set
the security status.  For RBTDB, it goes something like this:

	get:
		if (cached status == pending)
			lock node lock
			read rdataset's status
			unlock node lock
			update cached status
		return (cached status)

	set:
		require that status cannot go backwards (e.g. OK to pending)
		lock node lock
		write rdataset's status
		unlock node lock
		update cached status