The value of tmnxOtuIfPmTtiTx specifies the Trail Trace Identifier
(TTI) for the Path Monitoring (PM) in the OTU overhead. This
identifier can be a string or a non-printable sequence of bytes.
Specifying a one octet string with the value '0xFF' along with
a tmnxOtuIfPmTtiTxMode set to the value of 'auto (0)' will reset
the TTI to the system generated value.