csc file?

The CSC is a set of customisations that run on first boot. For example it will install a custom background, and operator specific programs like 'my t-mobile' to check your balance.

The CSC is also used by NPS to check what region/operator you're on, and then lookup the latest firmware for that region/operator and offer u an update if there is one.

You don't really need a CSC, as you'll have a cleaner setup. BUT NPS won't offer you updates without a CSC. You'll need to rely on odin and firmware from the community to update.