You can assign products to more than one category within and across catalogs.
For example, your master catalog has an electronics category with Cell Phones, Computers, and Televisions subcategories. In your storefront catalog, you assign the last year’s model televisions to two categories: Televisions, and Electronics Sale. In addition, you have a micro site where you sell clearance items. In your micro site catalog, you can also assign last years television models to the Clearance Televisions category.