Client Menu Reference : The Metadata Menu : New Category
   
New Category
Creates a category under the currently selected category, named “Category”. This name can be changed immediately to a more fitting one. (Disabled unless a single category is selected.)
New Related Category
Makes a related category for each of the currently selected categories. (Disabled unless one or more categories are selected.) (See “Category Types”.)
New Master Category (optional)
Opens a window to enter a name for the new master category that will be created under the currently selected catalog category. A master category has its own category tree. (Disabled unless a catalog category is selected. Available with Enterprise or a special option only.)