When you generate a DDR3 UniPHY IP controller with the option "Enable Error Detection and Correction Logic" turned ON, a 4 bit error output signal, local_rdata_error [3:0], will be generated in 11.1SP2 and older IP versions. All 4 bits behave the same and only bit 0 of local_rdata_error signal should be monitored. The other 3 bits can be ignored.
Device Family: Stratix® IV GX
Area: EMIF, Intellectual Property
IP Product: DDR3 SDRAM Controller MegaCore supporting UniPHY
This issue will be fixed in a future release of Quartus® II software and IP.