What is that strange title ?

Not a gender...well...if you've been programming computers, you know that common error message "not a number"...that is what I had in mind when I chose the title of my blog. My very own gender, neither woman (although I have female genitalia), neither man (since I don't want to go on T and all that stuff) is "not a gender" from the point of view of most people. I only wish it could be accepted, and be no more an error...