Government information: http://www.immd.gov.hk/eng/useful_information/non-stamping-immigration-clearance.html
As per normal procedures, I was given a Landing Slip while visiting Hong Kong (my suspicion being that it's because of Hong Kong's relationship with China).
I've since left Hong Kong, but I haven't yet returned to my home country, and will be visiting China later on in my trip.
Is it safe to dispose of my landing slip at this stage? If not, is it safe to do so once I return to my home country?