An ASCII text file (with the extension .xrf), that is generated by a third-party synthesis tool, and which allows the Quartus^® II software to locate or cross-probe an object from the Quartus II source design file to the third-party tool source design file.

The XRF provides mapping information between signals or components used in the third-party generated source file and signals or components used in the Quartus II design source file.

The XRF has the same name as the Quartus II project, and is located in the Quartus II project directory.