
Alright here is a more complete answer so Laurie might stop saying things about me that are true. Although we do need to swap the location of wonderful and somewhat in the description.
In Japan this is called 絶対領域, the term translates to "absolute territory" if we are talking about OTK boots, stockings or equivalent - and a skirt. The distance has been analyzed by clever grasshoppers and a formula derived of 4:1:2.5. The laws of physics meet biology, also known as the Golden Ratio.
4.0 = skirt length ratio
1.0 = proportion of skin showing between boot and skirt
2.5 = ratio covered above the knee
I have looked at some of Leonardo DaVinci's drawings but alas, while the Italians gave the world so much greatness (ballet, the violin, and cars that leak oil) the Codex Leicester which is owned by one of my neighbors contains none of this magic. (That particular neighbor started a software company in 1975 that provides unparalleled support for transgender employees - even those that get a bit out of line like myself.)
The world's most beautiful mathematics had to wait a few centuries for the technological zen of Japan. I am so glad the patent expired.