Biracial/ multiracial identification

Ka

Just curious but, how are biracial or multiracial people identified on their driver's license, birth certificate, etc.? I've heard it's by what race their father is, or by the most "prominent" racial characteristic (skin tone). So what if the parent(s) are biracial or multiracial as well?

Ps. Not that it matters what race you are, I'm just a very curious person 😂