yetanotherusernameAgain Ah I didn't know about the indigo, interesting. I believe the point I was trying to make was even simpler:
visible violet light has a specific bandwith around 320 nm, but you can also arrive at violet by mixing the color red (~700 nm) and blue (~480 nm). It looks violet, and yet, you won't find any violet light (320 nm) in it but only components of lower energy.
What the sex=spectrum people mean, as far as I gathered from discussions, is that sex is not just gamete / gonads but additionally:
hormone status, brain structure (even if science hasn't yet demonstrated it, 'there are pink and blue brains' they say), uterus....
Now think that through (let's award one point for each feature):
Transwoman gets one point for pink brain and one for hormone status: 2/4
A postmenopausal woman, who has had a hysterectomy and is the Peachy Yoghurt type of 'unfeminine' person gets only one point, for her gonad system that once produced female gamete: 1/4
This is how their 'spectra' idea works. That estrogen shots make them 'more of a woman', and postmenopausal women or those who do not conform to stereotypes 'are not real women'.