Hi Gunter,
I wrestled hard to make understandable user prompts, but fell short of the mark:-)

The prompt "Select unwrap center point" should be "Select any point in the view, to become the apex of the unwrap."

The prompt "Select Cone Face" should be "Select face of the cone, or face of the Frustum. A frustum is a cone with the top cut off. The face is the surface of the cone or frustum"

The prompt "Select Base Circle" should be "Select the Base Circle of the cone or Frustum"

The prompt "Uncheck Box for Cone, THEN select slant seam" should be "For a Cone, Uncheck the checkbox, then select the slant seam of the Cone. For a frustum, just select the slant seam of the Frustum. A slant seam is the edge of the cone or frustum which connects the Base circle to the apex of the Cone, or the top circle of the Frustum."
(A better way would be to have the user select either a cone or a frustum from the outset, and have separate menus.
But I find that the .htm is very difficult to write. MoI's stock commands, for example Circle, have XML code to pop up separate menu's for each circle type.
I find that some of Michaels examples of .htm are very complex. I am currently wrestling with combining two similar scripts into one. It is difficult for me.)

I did not write code to unwrap a curve or hole in the cone/frustum, even though it is possible using a bunch of curve points, because FLOW should accomplish that.

- Brian

(Note that a mathematical cone has two halves. In common talk, a cone is just half of a mathematical cone... The definition of a frustum, how to spell it, and
the meaning of a "slant seam," or "face," are not commonly known.)