Cubic Interpolation - someone saved a few too many characters with that name. So...

Cubic Interpolation - someone saved a few too many characters with that name.

So, that function uses opcode "c", which is documented here in SVG

Now it makes sense... but that took help from the internet and a lot of time to figure out.

Is it just me, or has actual documentation been abandoned in the last 20 years?

[Edit] I accept it's not a commercial production, but if you want to drive adoption of a proposed new thing, proper documentation would greatly help.