This notification field reports whether the software upgrade that triggered the associated event was performed as a graceful upgrade, true, or not, false. A graceful upgrade is designed to minimize traffic disruption during the software swap, so an admin correlating this flag with any observed traffic loss during an upgrade window can tell whether the disruption happened despite the graceful mechanism being used, worth escalating as a bug, or because a non-graceful upgrade was deliberately or accidentally chosen instead. For example, if this reads False(2) for an upgrade that caused a noticeable traffic interruption, the admin should check why graceful upgrade wasn't selected for that maintenance window.