Description
In the Intel® Quartus® Prime software, the VREF_MODE Quartus Settings file (.qsf) assignment can only be set to VCCIO_xx for the POD12 I/O standard when usong Intel Arria® 10 devices. The other I/O standards only support EXTERNAL VREF_MODE.
Resolution
This additional information is scheduled to be added in a future update of the Intel® Arria® 10 Core Fabric and General purpose I/Os handbook.