What should a Hong Kong passport holder write in the ‘Place of Issue’ field when applying for a Thai DTV in Hanoi?

For those who have successfully obtained their DTV with a Hong Kong passport.

I’m going to apply in Hanoi soon and would like to ask — as a Hong Kong passport holder, what should I write in the ‘Place of Issue’ field? Should it be ‘China’ (the code of the issuing state) or ‘Hong Kong’ (the issuing authority)? Both are shown on the passport’s bio-data page.

Thank you!