What is the difference between Line 0 and 1 for Cnet (C) and Cnet (SC) in Melody?

Attach is the data of some of controller station (PM875). Please find attach the image of the same. Want to know what exactly the difference between Line 0 and 1 for Cnet (C) and Cnet (SC) in Melody and how it relates to terminology (nomenclature) on the Melody Hardware.