I have a curious question. A Vietnamese of mine (she is in her 30s) says that the birth-date shown in her ID is in accordance to the Chinese (Lunar) calendar - meaning, (say) October 20 is not the October 20 of the Gregorian calendar, but the 20th day of the 10th month in the Chinese (Lunar) calendar. I wonder if what she says in correct. It is the practice of the Registry of Birth of the Department of Social Security in the past (whether in North or South Vietnam) ever used the birth-date of a person according to the Chinese calendar to be stated in the Birth Certificate or ID of Vietnamese citizens? I am very curious about what my friend says. Can somebody please clarify. Thank you!