Categories can be arranged in a nested, hierarchical way. When a category has one of more subcategories, it is considered to be the parent category. When assigning a parent category, you can enter the code for the parent category directly, or look up the category and select it from a list of all existing categories.
To assign a category to be the parent category for the one you are editing, locate the category in the list, and click Select. If you have many categories, to locate the one you need enter some part of the category name or code in the Search box, and click Go.