Here's the safety message... "Do not stand up, no leaning". It's mixed dynamics here..'Do Not Stand' rather than "No Standing", and equally "No Leaning" rather than "Do Not Lean".
A shorter and more consistent message could have read "No Standing or Leaning", or "Do Not Stand or Lean". There's probably an emphasis here though on the process of standing up....it's that rapid movement of the centre of gravity, and especially while the train is in motion. Probably less severe or volatile impact with just leaning.
And technically you'd be standing, both before sitting down for the journey and then afterwards to get off.....
