Fires whenever a control segment is read that marks the start of an interchange.
The 'callback' is called when the 'StartInterchange' event is emited.
The argument 'e' has the following properties:
e.tag e.controlNumber e.fullSegment
The StartInterchange event will fire when a control segment marking the start of an interchange structure is read. The Tag parameter contains the tag of the segment, such as ISA. ControlNumber contains the control number associated with the segment.