The XCVR_REFCLK_PIN_TERMINATION, DC_COUPLING_INTERNAL_100_OHM assignment fails in Quartus® software version 12.0 due to a typing error in the transceiver PHY IP userguide.
"Table 6-4. Transceiver and PLL Assignments for Stratix® V Devices" of the transceiver PHY IP userguide details the constraint as"DC_COUPLING_INTERNAL_100_OHM". The correct constraint is "DC_COUPLING_INTERNAL_100_OHMS"
This documentation error will be fixed in a future release of the user guide.