An ASCII text file (with the extension .bsd) that uses Boundary-Scan Description Language (BSDL) to provide information for JTAG boundary-scan testing of an Altera device.
You can download BSDL Files from the BSDL Files section of the Altera website at www.altera.com. BSDL Files are available only for Stratix IV devices and later. Each BSDL File has been checked for syntax and tested for functionality, and can be used regardless of a device's speed grade or temperature.