Fnord wrote:
Suggestion: Start with the genetic definition ("XX" = Female, or "XY" = Male), then work out the actual label you want from the "equipment" attached to your body.
Or pick one at random.

The genetic definition already leaves out a substantial number of people. Roughly one in 500 people born with male physiology are not genetically male, they are intersexed, with an XXY karyotype. That works out to 300,000 people in the United States, alone. On the "female" side, there are the people born missing a chromosome.
Physiologically there are plenty of people who cannot define themselves, eitehr. There are the people whose sexual organs never develop, or underdevelop.
And that doesn't even touch on the issue of those whose physiological sex and psychological sex are inconsistent with each other.
My suggestion is fill out nothing that does not fit. If the list of options does not include, at a minimum, an "other," option, then don't buttonhole yourself as male or female if you are neither.
_________________
--James