What is saved on the 72hours or 144 Hours QR CODE

Q1:
What is saved on the 72hours or 144 Hours QR CODE on the VISA at Arrival?
Q2:
I am worried about it because i want to book the route SIN-KUL-PVG-KUL-SIN and i am not sure if i am qualified for a 72 or 144 hr free Transit. So i will book a additional Flight PVG to HKG which i won t use. I just want to show the Immigration my return flight ticket to a third Country (HKG)?

Again i want to fly only SIN-KUL-PVG-KUL-SIN (without leaving the Airport in KUL its just Transit) am i qualified or not? If i am not Qualified i will still Keep the same route but i will Show the Immigration that i am Holding a ticket for third Country HKG which i will never fly too.
Thank you