Hmm. So what would qualify something as a dream within a dream, by your definition? Would it be sufficient for the outer dream to successfully both save and restore a context around it (so that I dreamed about doing X, then falling asleep, then doing some other thing Y, then "waking up" and continuing to do X where I'd left off)? Or would the inner dream have to have some perceptible quality of dreaminess that the outer one hadn't?