NUKE keyframes animation curve

Question

I'm parsing the NUKE software keyframe animation format. It's description is here: https://learn.foundry.com/nuke/developers/70/ndkdevguide/advanced/curveformat.html

It uses these numbers to define the curve. ("x" x-value) y-value ("s" l-slope) ("t" r-slope) ("u" l-angle) ("v" r-angle)

x,y,slope are fine, but I'm confused by the "angle". I'm assuming l and r refer to left and right side of the anchor point. The l-angle and r-angle seem more like a function of the length of the handle to me. It also seems like the maximum value is 3

Below are some examples with image (note, the grid in the images doesn't show units "correctly", but the slope values mean what you'd think they mean, they say how much increase in y per x value)

x40 399.5495605 s21.10000038 u3 v0.9411216378

Here's another example, note l-angle is still 3 (the maximum, but I had to decrease the slope)

x40 399.5495605 s5.900000095 u3 v0.9411216378

Another one:

x40 399.5495605 s6 u0.2508043051 v0.9411216378

And an example where l-slope and r-slope is different, neither u,v are provided, so per docs default to 1 (whatever that means)

x1 355 x40 399.5495605 s6 t-6.953211784

Anyone have ideas about what the "angle" values mean in this context? I'm trying to convert this format into the more normal bezier curve definition.

(I also posted this question in a NUKE forum: https://community.foundry.com/discuss/topic/160372/curve-serialisation-format)

EDIT: (about the grids not showing "correct units")