ES Event Location... File as a Data Source

Can you help me understand a bit more about the 'FILE AS DATA SOURCE' option that shows in the Location custom field for events? What it is and how to use it?

I have turned off Google Maps because it doesn't cover my part of the world very well... my objective now is to offer users a short tailored pick-list of local locations for them to choose from.

It sounds like 'FILE AS DATA SOURCE' might achieve this for me. Alternatively I'm thinking I can use the COUNTRY drop-down and hack the countries listed with my list of locations? (If I do that, does EasySocial pick up and display the Country field as the location - hopefully it does)

Thanks!