Upstream Histogram is a PNM Test described in [PHYv3.1] Upstream Histogram section. The CmtsUsHistTable defines the management interface for the operator to configure, execute, and monitor the Upstream Histogram test. The Upstream Histogram provides a measurement of nonlinear effects in the channel such as amplifier compression and laser clipping. For example, laser clipping causes one tail of the histogram to be truncated and replaced with a spike. When the UpstreamHistogram Enable attribute is set to 'true', the CCAP will begin capturing the histogram of time domain samples at the wideband front end of the receiver (full upstream band). The histogram is two-sided; that is, it encompasses values from far-negative to far-positive values of the samples. The histogram will have a minimum of 255 or 256 equally spaced bins. These bins typically correspond to the 8 MSBs of the wideband analog-to-digital converter (ADC) for the case of 255 or 256 bins. The histogram dwell count, a 32-bit unsigned integer, is the number of samples observed while counting hits for a given bin, and may have the same value for all bins. The histogram hit count, a 32-bit unsigned integer, is the number of samples falling in a given bin. The CCAP will report the dwell count per bin and the hit count per bin. When enabled, the CCAP will compute a histogram with a dwell of at least 10 million samples at each bin in 30 seconds or less. The CCAP will continue accumulating histogram samples until it is restarted, disabled or times out. If the highest dwell count approaches its 32-bit overflow value, the CCAP will save the current set of histogram values and reset the histogram, so that in a steady-state condition a complete measurement is always available. The CCAP creates a row in the docsPnmCmtsUsHistTable for each ifIndex of an upstream RF port. The CCAP MAY support simultaneous Upstream Histogram tests on more than one RF port at a time. The CCAP should reject configuring a value for the DestinationIndex of the UpstreamHistogram object if that value does not exist in the corresponding DestinationIndex attribute of the DataTransferCfg instance