You specify the attribute that is to be sent and received through the flow port by giving the attribute and flow port the same name. If no attribute name matches the name of the flow port, a warning to this effect will be issued during code generation.
Atomic flow ports allow the flow of only a single primitive attribute.
When connecting two atomic flow ports, you have to make sure that one is an input flow port and one is an output flow port. The type of the attribute in the sending and receiving objects must match.