The description of the elements is followed by the description of their connections to each other, i.e. the dataflow. For ports connections the description starts with the .actor-bindings keyword and has the following format:
This pair says that data from port1 of element1 will be transferred to port2 of element2. For slots the following format without start keyword is used:
This pair says that data from slot1 of element1 will be transferred to slot2 of port2 of element2. See, for example, the minimum description of a dataflow of a workflow, that aligns an input MSA and writes the result to a file in ClustalW format.