The next step is to define the dynamic mappings, which are composed of fields that need to be passed from the incoming format to the outgoing format. In this case it's the Message's Date/Time and Message Control ID fields. These two fields are the unique identifiers for each HL7 message.

You need to define and map an intermediate table to carry these fields - call this table MSHTable. This table needs to map to and from the MSH segment in both formats.