The aluDslPortNtrErrorHistory is an array of bytes used to indicate phase error history. Each byte represents the phase error between the encoded phase information (as present in the NTR field of the overhead frame) and the CPE regenerated NTR clock. Therefore each byte indicates the phase error between the CO NTR clock and the CPE regenerated NTR clock. These values are expressed in clock ticks based on the aluDslPortNtrSampleClockPeriod. The time interval between bytes in this array is 1/16 of a second It is applicable only when the value of tmnxPortType is 'XDSL'.