Initially i thought they were saying "non standard", but no they are saying "on standard".
However they never use the term "flight level"... So i take it as meaning to climb to the cleared level and change the altimeter as normal at transition.
E.g. "climb 8400m on standard" means climb to flight level 8400m.
Of course there are also instances when they will clear you to a flight level below transition on arrival. Tianjin does this regularly, by transmitting "descend 3000m on standard"