Fires whenever a control segment is read that marks the start of a transaction.
The 'callback' is called when the 'StartTransaction' event is emited.
The argument 'e' has the following properties:
e.tag e.controlNumber e.code e.fullSegment
The StartTransaction event will fire when a control segment marking the start of a transaction is read. The Tag parameter contains the tag of the segment, such as ST. ControlNumber contains the control number associated with the segment. Code contains the transaction code (such as 810).