Split single face of solid with either an Isocurve or other Crv?

If I have a cube, and I want to split only one face in a specific spot, so i can then extrude that partial face, is this possible? See attached (and for some reason Rhino decided it couldn’t let go of that text, so it’s forever selected and can’t delete :roll_eyes:)

The idea would be to do what Sketchup does when you draw a line across a face.

SplitFace, then subobject select the new face and use ExtrudeSrf to get where you want.

So what you’re saying is, in order to “split a face” I should use “SplitFace.” Hm. Genius. :joy: