Vistation to Shanghai

Your assumption is correct.

Thanks for the prompt reply.
Last year when I visited other parts of China under 72 hour-free scheme, I was stuck to the airport in Colombo when departing.
The airport staffs required me to submit the proven document about this free trip, which I didn't have.

Therefore, I am wondering if we have any proven documentation about this policy.
This time, I don't want to spend my time on airport by same reason. Please help me.

Thanks

Chinese carriers are well-informed of this policy. However, if you are flying with other airlines, tell them to either call immigration themselves or inquire with TIMATIC, which is a tool the airlines use for visa information regarding a destination country. Also you need to tell them you are in transit to a third country or region (Hong Kong) when running a TIMATIC check and bring proof of your onward reservation. The TWOV policy has been in place for well over 5 years now (was upgraded to 144 hours two and a half years ago) so make sure you properly lecture them and their supervisors if possible.