json - What is a good alternative to Unix time for encoding date of birth? -

i use unix time date of birth, doesn't work date of birth because unix time starts in 1970.

i'll sending date of birth json. make sense use unix time negative numbers? or there standard works better?

this api, working multiple clients, want use standard, simple convention. yyyymmdd seems confusing , error prone.

the international organization standardization (iso) advocates yyyy-mm-dd.

the world wide web consortium (w3c)'s quality assurance interest group (qaig) comments:

albeit not perfect, iso date format is, however, best choice date representation universally (and accurately) understandable. [link]

and think technically-minded people recognize it.