On the student information forms sent home for updated contact infomation, why are the only choices for parents' marital status "together," "separated," or "divorced?" Where is married?

The fact that the question requests "marital status" implies that there is a marriage involved. Although there may be many ways to define one's marital status, the intent is to determine if the parents are "together" under the same roof or "not together" under the same roof with the legal issues that either "separated" or "divorced" would potentially create for a school.