the ID of the element being referenced. The name of the instance being referenced. The type of item being referenced (should correspond to the name of the referenced XML element). The version of the element being referenced. A non-CIM (non-GUID) id used to reference the element in question. A description of the element being referenced, in the context of the current class. An optional description of how the item being referenced has been modified. This is particularly useful for dealing with Ensembles (a set of simulations where something about each simulation has changed) or Conformances.