I would be curious to know why it is not possible to create an edgesrf using one, closed curve.

In other words, why do I have to split a closed curve in 2 to use it for edgesrf rather than have the option to use 1 curve?

I would be curious to know why it is not possible to create an edgesrf using one, closed curve.

In other words, why do I have to split a closed curve in 2 to use it for edgesrf rather than have the option to use 1 curve?

If the curve is planar, I recommend using PlanarSrf command. It’s my favorite command

A surface has two dimensions U and V. But a closed curve has only one dimension.

So at some place it needs a split.

They are non planar, closed curves.

There are effectively planar curves bent upwards.

One closed curve or a number of curves, which one? if a number of curves, then use NetworkSrf maybe.

These are single, closed curves.

My guess is the reason EdgeSrf requires a minimum of two curves because the output of EdgeSrf is an untrimmed NURBS parametric surface. An untrimmed parametric surface requires at least two non-zero length edges.

The output of PlanarSrf can be a trimmed surface.