table 3-6. UTF-8 bit distribution

[Dominikus Dittes Scherkl]

Am 11.09.25 um 21:21 schrieb yitin--- via Unicode:
> https://www.unicode.org/versions/Unicode16.0.0/core-spec/chapter-3/#G27288
> 
> What is the significance of using different letters (x,y,z,u)
> for different bits?

Significance? None.
This is simply to enhance the Readability: shows witch bits of the 
encoding represent witch bits of the scalar value.