
Those citizens who are biologically not entirely male or female have the third category. Moreover, birth certificates will not have to be changed to claim the third option.
U.S. rules were changed last year for transgender people. However, certification of a surgery is still required to qualify (though not sexual reassignment surgery):
Beginning June 10, when a passport applicant presents a certification from an attending medical physician that the applicant has undergone appropriate clinical treatment for gender transition, the passport will reflect the new gender. The guidelines include detailed information about what information the certification must include. It is also possible to obtain a limited-validity passport if the physician’s statement shows the applicant is in the process of gender transition. No additional medical records are required. Sexual reassignment surgery is no longer a prerequisite for passport issuance. A Consular Report of Birth Abroad can also be amended with the new gender.
Source: Daily Mail
