Required Items in WMI Classes

All class definitions except embedded classes must include the items InstanceName and Active, which must appear exactly as shown:

//WMI class definition
[
    //Class qualifiers
]
ClassName : BaseClassName
{
    [key, read]
     string InstanceName;
    [read] 
     boolean Active;
 
    // Driver-defined data items
}

The InstanceName and Active items are required and used internally by WMI. The MOF class definitions of a driver's data and event blocks must include these items, but the driver must not set these items when responding to a query for the data block or sending an event, because they are not part of the driver's data block.