The letter nonbinary people, who see themselves as neither male nor female, want to use on
identification documents like their birth
certificate or passport to reflect their gender—preventing them to do so would force them to lie about their true identity.
Although a number of
countries allow their citizens to use X and O (for “others”), rather than M or F, on their passport to
identify themselves, however, the odds of their being denied entry by border control
authorities elsewhere are never zero.