Actual Aggregate Transmit Power Downstream.
The total amount of transmit power delivered by the xTU-C at
the U-C reference point, at the instant of measurement. It
ranges from -310 to 310 units of 0.1 dBm (Physical values are -31
to 31 dBm).
A value of 0x7FFFFFFF (2147483647) indicates the measurement is
out of range to be represented.
This object reflects the value of the parameter following the
most recent DELT performed on the associated line. Once the DELT
process is over, the parameter no longer changes until the row is
deleted or a new DELT process is initiated.