The upstream PSD mask applicable at the U-C2 reference point. This parameter is used only for G992.3 or G992.5 and it may impose PSD restrictions (breakpoints) in addition to the Limit PSD mask defined in G992.5. This is a string of 32 pairs of values in the following structure: Octets 0+1 - Index of 1st sub-carrier used in the context of a first breakpoint. Octet 2 - The PSD reduction for the sub-carrier indicated in octets 0 and 1. Octets 3-5 - Same, for a 2nd breakpoint. Octets 6-8 - Same, for a 3rd breakpoint. This architecture continues until octets 9-11, which are associated with a fourth breakpoint. Each subcarrier index is an unsigned number in the range 1 and NSCus. Each PSD reduction value is in the range 0 (0dBm/Hz) to 255 (-127.5dBm/Hz) with steps of 0.5dBm/Hz. Valid values are in the range 0 to 190 (0 to -95dBm/Hz). When the number of breakpoints is less than 4, all remaining octets are set to the value 0. Note that the content of this object should be correlated with the sub-carriers mask and with the RFI setup.