Just a note on the "***" symbol: it indicates that the holder of the HK ID card is of the age of 18 years or over and is eligible for a Hong Kong Re-entry Permit.
The Hong Kong Re-entry Permit is a document issued by the HKSAR government to facilitate travel to and from mainland China and/or Macau. At present, the following persons are eligible for a Hong Kong SAR Re-entry Permit:
(i) Chinese citizens who have either acquired the right of abode in Hong Kong or been granted unconditional stay in Hong Kong; and
(ii) non-Chinese citizens who have the right of abode in Hong Kong but cannot obtain national passports and do not hold travel documents of any other countries or regions.
"*" indicates that the holder of the HK ID card is of the age of 11 years - 17 years old, and is eligible for a Hong Kong Re-entry Permit.