Category sets contain different "classes of categories".

In other words, the purpose of the category sets is to separate the categories of different classes.

For example, you may want to have a similar but not exactly the same categorization of the paper products and of the Web products. Therefore, you will use MainCategories for paper products, and WebCategories for Web products.

Another example, you need different categorization for events/tasks and for articles. Therefore, you will use MainCategories for articles, and calendarCategory for events/tasks.

See also

Default category sets