nwDecIVEventTraceAll is a read-write switch where enabled(3) logs all event types on all router ports for all protocols and components, and disabled(2) instead relies on the separate event filter table to decide which specific events get logged. An admin enables this for broad, unfiltered troubleshooting visibility, or disables it and configures targeted filters to avoid flooding the log with events they don't care about. For example, an admin doing a deep investigation into intermittent DECnet failures might temporarily set nwDecIVEventTraceAll to enabled(3) to capture everything, then switch back to filtered logging once the issue is found.