WITSML - Product Flow Network External Port Component Schema. The name of the external port within the context of the current Product Flow Network. Defines whether this port is an inlet or outlet. Note that this is a nominal intended direction. Defines the internal node to which this external port is connected. All ports (whether internal or external) that are connected to a node with the same name are connected to each other. Node names are unique to each network. The purpose of the external port is to provide input to or output from the internal network. Similar to a node, there is no pressure drop across a port. Thus, if another external port connects to the same node as this external port, there should not be an internal pressure drop across those ports. Also similar to a node, conservation of mass exists across the port and the flow direction across the port can change over time if the relative pressures across connected units change. A descriptive remark about the port. Unique identifier for the port.