This configuration parameter defines the upstream PSD mask applicable at the U R2 reference point. This MIB PSD mask may impose PSD restrictions in addition to the Limit PSD mask defined in the relevant Recommendations (e.g., ITU-T Recommendations G.992.3, G.993.2). This is a string of 16 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 45-47 - Same, for a 3rd breakpoint. This architecture continues until octets 45-47, 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 (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 16, all remaining octets are set to the value 0xff. Note that the content of this object should be correlated with the sub-carriers mask and with the RFI setup.