With otherunit specified
nil = unit is not on otherunit's threat table.
0 = not tanking, lower threat than tank.
1 = not tanking, higher threat than tank.
2 = insecurely tanking, another unit have higher threat but not tanking.
3 = securely tanking, highest threat
Without otherunit specified
nil = unit is not on any other unit's threat table.
0 = not tanking anything.
1 = not tanking anything, but have higher threat than tank on at least one unit.
2 = insecurely tanking at least one unit, but not securely tanking anything.
3 = securely tanking at least one unit.