Bring your whole self to work is what my employer tells me. Unless of course you happen to believe like I do that sex is binary and fixed from conception. In that case I am allowed to hold that belief (thank you Maya), but not to express it plainly in case it causes offense to those who believe that the concept of innate gender identity is more important in all cases than biological sex, or somehow denies their identity.
But what about my identity?
When my employer asks for my gender but not my sex, or asks for my gender without giving me the option to say that I do not believe in an innate gender, this denies my identity. My sex is important to me. My sex has shaped my life. During my career I have experienced sexism, disadvantage and discrimination due to my sex and I have had to fight against the stereotypes imposed upon me due to my sex.
When my employer asks me to state whether I identify as a woman, this denies my identity. To use woman in this way is to change it from a definition based on sex, to one based on gender identity. I am not a woman because I have womanly thoughts and feelings which are separate and distinct from manly thoughts and feelings - and if you think I am you need to reconsider as this is the very definition of sexism.
When my employer allows me to be referred to as cis-gendered, this denies my identity. I am not a woman because my personality happens to align with the stereotypical expectations that society places on me due to my sex, any more than I would not be a woman if my personality did not. And my personality, like that of everyone else I have ever met, is a mix of those traits that society ascribes to be feminine and masculine because stereotypes are nonsense.
I am a woman because my sex is female. But knowing my sex tells you nothing about me except what my sex is. It does not tell you about my personality, my likes and dislikes, my strengths and weaknesses. There is no trait, characteristic, thought or feeling that I share with all other women on this planet and which is distinct from those shared by men, other than our biology. So I say again, I am a woman because my sex is female.
We are all afforded protections in law to prevent us from suffering from discrimination and harassment or to preserve our privacy and dignity because of our sex. But as it stands my employer has no record of my sex and has replaced sex with gender and that is why SEEN is so important to me.