This property determines the path identifying the OPC Block on the server to which the OPC Driver connects. Definition of this path is flexible and depends on the specific server. Usually, servers specify an ID space with hierarchical items, such as ParentItem.ChildItem.Tag1. The ItemID property works as a unique key for data, considering where or what allows an OPC server to connect to a data source. Although its default value is empty, users must specify a value for this OPC Block to be valid.