Hi, Prospectus says they rank below NSN? I'm always a little...

Hi,
Prospectus says they rank below NSN?
I'm always a little confused about the rankings of some of these securities on winding up, as the non-viability trigger seems to send them all to the same place, ord shares, or being written off completely[exception being nabha].
I also find it hard to value the risk that the somewhat undefined, non-viability trigger clauses present.
This new one seems a dog, interest rate not high, non-viability trigger[which, and please correct me if I'm wrong, makes the ranking a moot point, or does the ranking effect the order in which they are converted?], no dividend stopper.
Positive: payments not discretionary[ which makes the lack of a stopper less relevant]

Nothing here that makes me enthusiastic about cashing in things like nabha, mblhb, and the few non-bank securities still floating around.

As far as the title of the thread, still have hopes that the bank will one day do a benhb type buy back, at a premium.
$80 dollars would be nice, but why would they, if issues like this one keep getting taken up?
cheers