There are flaws in description of SelectionFilter sub-objects. SelectionFilter documentation is here: https://docs.mcneel.com/rhino/6/help/en-us/commands/selection_commands.htm#SelectionFilter
Selection Filter options…
Allows sub-object selection.
As a matter of fact, this filter checkbox is not necessary to select sub-objects, because sub-objects can be selected by holding down Ctrl+Shift keys. The checkbox makes it unnecessary to hold down Ctrl+Shift keys. If the keys are held down, the sub-object selection is disabled.
Restricts selection to polysurface objects.
It should say: Restricts selection to polysurface objects, and with sub-object selection checked, polysurface faces.
The SelectionFilter command is at the bottom of the Selection Filter chapter. I would move it to the top of the chapter.
Separate topic: CurvePiping, Thickness, EdgeSoftening, Shutlining, and Displacement are mesh modifiers, but they are not clearly defined as mesh modifiers.
Another topic: ApplyCrv documentation is here: https://docs.mcneel.com/rhino/6/help/en-us/commands/createuvcrv.htm
It says: You must then also map the u and v curves along with the curves you are applying so they will act as a placeholder.
What does it mean?
The next sentence says: Use the CreateUVCrv command to generate planar versions of the u and v trim curves of a surface so you can use them as a guide to orient your text.
Speaking in plain English, the u and v trim curves make up rectangular boundary of the NURBS surface.
1. Select objects on world xy plane to apply to a surface.
More info should be provided about these objects. One of them is (generally rectangular) NURBS boundary. The rest are planar curves inside the boundary.