What does birthdaySet mean in the response of the users.getCurrentUser method?

Question

API

Good afternoon!
When calling the users.getCurrentUser method in one particular case, the following response was returned:
{
"uid":"571883382614",
"birthday":"01-01",
"birthdaySet":false,
"first_name":"ABS",
"last_name ":"Abs"
}
This user's profile contains the date of birth 1970-01-01. Question. What does the birthdaySet field mean? This is the only case I know of where it returned false. Why does birthday have such a strange meaning? Is it true that once in Odnoklassniki it was possible to create profiles without indicating the date of birth?

Answer 1

Means that the date of birth is not set for the user. And the strange date is the beginning of the Unix era. Time is measured as the number of seconds since that date - so if it's filled with 0 - that date will be there.