property Items.ItemData(Item as HITEM) as Variant

Retrieves or sets the extra data for a specific item.

   Item as HITEM A long expression that indicates the item's handle that has associated some extra data.  
   Variant A variant value that indicates the item's extra data.  

Use the ItemData property to assign an extra value to an item. Use CellData property to associate an extra data with a cell. The ItemData and CellData are of Variant type, so you will be able to save here what ever you want: numbers, objects, strings, and so on. The user data is only for user use. The control doesn't use this value. Use the Data property to assign an extra data to a column. For instance, you can use the RemoveItem event to release any extra data that is associated to the item.