public virtual Category this[
	BuiltInCategory categoryId
] { get; }

Public Overridable ReadOnly Property Item ( _
	categoryId As BuiltInCategory _
) As Category
	Get

public:
virtual property Category^ Item[BuiltInCategory categoryId] {
	Category^ get (BuiltInCategory categoryId);
}

Unlike the method that obtains categories by name, this routine will obtain the handle even of built-in subcategories. Since 2016 it is advised to use either [!:​Autodesk::​Revit::DB::​Category::​GetCategory(​Document,​BuiltIn​Category)] or [!:​Autodesk::​Revit::DB::​Category::​GetCategory(​Document,​ElementId)]​ method from Category class.