This is what the immigration replied to me.
Going back to your enquiry and according to your information, you are not holding a Hong Kong permanent identity card which was issued on or after 1 July 1987 and before 23 June 2003. [ A permanent identity card bears a symbol “A†beneath the Date of Birth at the front side and state "HONG KONG PERMANENT IDENTITY CARD (The holder of this card has the right of abode in Hong Kong)" at the back side. ]
You are holding the invalid old type Hong Kong identity card issued on 15-11-1991 bearing "U" code which means that you enjoy "unconditional stay" at the time of your Hong Kong identity card registration.
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