Hi Jove,
As I mentioned in my earlier replies, whenever you create Site in IS Retail it creates a local assortment for each site. If your site is Store, the assortment category will A, for DC it will be B. Category C is used for assortments which are defined by the user. All the assortment what we create explicitly to cater our listing requirements will be automatically created with category C.
So Customer means the Customer defined assortment.
I hope this will clarify your question.
Regards,
Amit