Certificates of Identity were issued to Hong Kong permanent residents who did not hold and could not obtain any valid travel documents for overseas travel. Normally, CIs were valid for ten years.
Since establishment of the HKSAR on 1 July 1997, no more Certificates of Identity were issued. Those already issued remained valid for travel until expiry (which may pass beyond 30 June 1997; as CIs were valid for a maximum of 10 years), none of which past 30 June 2007.
CI were not used to enter Mainland China or Macau.
Read more about this topic: Hong Kong Certificate Of Identity