The format of the SNMP trap PDU to be sent to this trap destination.
v1 Trap-PDU defined in RFC1157, encapsulated in the message
structure also defined in RFC1157.
v2c SNMPv2-Trap-PDU defined in RFC1905, encapsulated in the
message structure defined in RFC1901.
v3 SNMPv2-Trap-PDU defined in RFC1905, encapsulated in the
message structure defined in RFC2571.