Function

1. If there are only one EL, each message, from the first to the last, is extracted from the EL. For each message the values of the fields are passed to the field variables and the code is executed. The code must have a SENDTO instruction for the message. The fields are updated before the message is sent to some list.
2. If there are many predecessors, there is one EL for each. Then a SELECT instruction must be executed, that selects messages from some EL and sent them to other nodes. See 6.22 for details of this instruction.