A system for a message trigger has the following properties.

Triggering

Select the system or systems that triggers the action. You must select at least one.

In Message

Select the system or systems that displays the message. You must select at least one.

Each message in a message queue includes the pkey_src_object value for each cross-reference that it has in one of the 'In Message' systems.

For example, your implementation has three source systems: A, B, and C. You select system A as the Triggering system. A base object record has cross-reference records for A and B. You want to update the cross-reference in system A for this base object record. The following table shows possible message trigger configurations and the resulting message: