NB: More recent documentation for Dyalog APL is available at https://docs.dyalog.com/20.0/.

DYALOG_EVENTLOGGINGLEVEL

This parameter applies under Windows only, and specifies whether a log entry is written to the Windows Event Log or not when Dyalog APL would pop up a message box due to an unexpected termination of Dyalog APL. See Handling Unexpected Application Errors in Windows for more information.