The upstream PSD mask applicable at the U-R2 reference point. This parameter is used only for G.992.5, and it may impose PSD restrictions (breakpoints) in addition to the Limit PSD mask defined in G.992.5. This is a string of 16 pairs of values in the following structure: Octets 0-1 - Index of the first subcarrier used in the context of a first breakpoint. Octet 2 - The PSD reduction for the subcarrier indicated in octets 0 and 1. Octets 3-5 - Same, for a second breakpoint. Octets 6-8 - Same, for a third breakpoint. This architecture continues until octets 9-47, which are associated with a 16th breakpoint. Each subcarrier index is an unsigned number in the range 0 and NSCus-1. Each PSD reduction value is in the range 0 (0 dBm/Hz) to 255 (-127.5 dBm/Hz) with steps of 0.5 dBm/Hz. Valid values are in the range 0 to 190 (0 to -95 dBm/Hz). When the number of breakpoints is less than 16, all remaining octets are set to the value '0'. Note that the content of this object should be correlated with the subcarrier mask and with the RFI setup.