The Horizontal or Vertical Checkbox Category Selector feature is available for WPSLP Premier or MySLP Enterprise level subscription customers. The checkbox works with an “OR” selection based on the Parent category. With Premier or Enterprise you will see additional category selectors under the Settings/Search/Category section. For example : If you check the  red and  blue boxes on the category selector it will show any location in the red OR blue category.
The ability to categorize your locations using the WordPress category (taxonomy) system. The Categories Manager (Formerly known as Tagalong) is part of the Power Add-on for WPSLP self managed customers, and available for the MYSLP Professional or higher plans) It builds on the Store Locator Plus store_page taxonomy that is also used with the Pages portion of the Power Add-on (for WPSLP stand alone). Build a “simple flat list” of categories or a hierarchical (parent/child) category structure. Once you’ve categorized locations you will find other added benefits on the user interface.