By default the Category is the fully qualified class name of the field being monitored. This is then added to the BaseCategory Property along with "Field Monitoring" to form the full category name.
By setting the Category property explicitly you can put a specific field into a subcategory underneath "Field Monitoring".
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