Per the G.SHDSL Standard G.911.2. This parameter allows selection for the modem to output a symmetric PSD at all rates or asymmetric PSD's at fixed rates of 776kbps or 1544kbps, for Annex A networks. Annex B networks support fixed rates of 2056kbps or 2304kbps. The setting of auto-detect is only valid for CPE to train off of COE PSD settings.