Grasshopper subcurve point domain

[intrinsic5 (airoaya)]

hi i’d like to extract a specific area on a surface
i have curves and point want to set as area
so i’d like to use subcurve comp but i dont know how to set a domain

How do I set up domain?

0530 subcurve.gh (19.4 KB)
subcurve.3dm (239.8 KB)