Hellow

pls :

--Seeing your tutorial 'Tween Curve on Surface':

Would it be possible to explain a little more those "four curves" that it takes to carry out the example?.

(To be able to adapt this definition to another/s forms).

I can't quite understand what each one of them refers to.....?.

What curves should I take if I start from another Brep?.

L0...L1...?PT/Crv?(Map to border)

Thank you