You can create arbitrarily deep categorization by using periods (.) to separate category levels. For example, the category "Database.Query.Search" will be parsed to create a three-level category {Database, Query, Search}. You can have spaces in the category name.
Requirements
Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2