This read-only object identifier holds the OID of the first variable binding included in the most recent SNMP trap this bridge generated. An admin uses this to quickly identify what kind of event triggered the bridge's last trap without needing to have captured the trap packet itself at the time it was sent. For example, if bdgdeviceTrapType shows an OID corresponding to a topology change notification, the admin knows the last trap this bridge sent was related to a spanning tree event rather than a port failure.