Hola,
I have found the following (check the link below as well):
TOS - trunk operational status
TAS - trunk administrative status
TNS - trunk negotiation status
TOT - trunk operational encapsulation type
TAT - trunk administration encapsulation type
TNT - trunk negotiation type
These indicators basically give you the status of the configured trunk on a specific interface.
http://www.freepatentsonline.com/6445715.html
HTH,
GP