Customer Ship-To categories are optional, additional data feeds that allow you to assign your different customer-ship-to (and by extension, customers) to different categories of information.
These categories can then be used as properties in your forecasting hierarchy, or simply for filtering in screens like the Sales & Margin screen.
In this settings screen, enable each of the 3 categories that you want to use and give it a name. These names should sync up with data provided in the StockIQ data feeds. the CustomerShipToCategory1 (2 and 3) data feeds provide the possible values, and the CustomerShipToCategories data feeds associates different ship-to identities to the desired customer categories.
The most common use for the Customer Ship-To categories is to use Customer Ship Category 1 to make forecast groups for the purposes of Hybrid Forecasting.