In viewing the latest excellent tutorials on “Better Living Through CNC” on YouTube, the topic of curve degree and curve spans has come up. The Alias Golden Rules was mentioned as a good reference for this and its rule #3 discusses curve span. I can’t figure out how, in Rhino, how to determine and control how many spans a curve has. Can someone enlighten me?

A single-span curve has degree+1 control points. Any more than that, the curve is multi-span. So a degree 3 single-span curve will have 4 control points and a degree 5 single-span curve 6 control points.

Nothing to be concerned about.
My push back point is this is the level of technical detail you need to understand the specific questions you’re asking.

Here’s a link to the same information in a more friendly accessible format: rhino_basics.pdf (2.5 MB)