This attribute shall be used to describe the direction of the Port. Values shall be one of the following: “In” or “Out” or “InOut”. Ports with the direction “In” can only be connected to ports with the direction “Out” or “InOut” and ports with the direction “Out” can only be connected with ports with the direction “In” or “InOut”. Ports with the direction “InOut” can be connected to Ports of arbitrary direction. Examples: Direction =”Out” (e.g. a plug) Direction = “In” (e.g. a socket) Direction = “InOut” This information can be used e.g. in order to prove the validity of a connection.