The <trace> element writes a message to the ObjectScript shell. <trace> messages appear only if the BPL business process that generates them has been configured to Run in Foreground mode.
Trace messages may be written to the Event Log as well as to the console. A system administrator controls this behavior by configuring a production from the Interoperability > Configure > Production page in the Management Portal. If a BPL business process has the Log Trace Events option checked, it writes trace messages to the Event Log as well as displaying them at the console. If a trace message is logged, its Event Log entry type is Trace.
The BPL <trace> element generates trace message with User priority; the result is the same as calling the $$$TRACE utility from ObjectScript.