To save the Trigger Event in a global variable:

• In the Workspace, double-click the MSH segment. The MSH Segment Definition window appears.

MSH Segment Definition Window

• Locate field 9, Message Type, and click the ellipsis button in the Inbound Script column. This creates a Segment Inbound script. This script processes the data contained in a field of the segment before the segment is parsed.
• In the Editing Script window, type the code shown below:

MessageType = field.subfield(1).value

This code assigns the second subfield of field 9 to a variable named MessageType. (Note that subfield(1) accesses the second element of field 9, not the first. To access the first field, you would use subfield(0).) When an ADT^A03 message is parsed, this code assigns A03 to MessageType.