It is used by compilers to create native executable files ( .exe on Windows, .so on Android) to run Super Mario 64 without an emulator.
Which (Windows, Mac, Linux) are you using for your tools? baseromusz64+download+link
: Once dumped, rename your ROM file exactly to baserom.us.z64 and place it in the main folder of your build tool. Troubleshooting "Failed to Open" Errors If your build tool says it cannot find the file: It is used by compilers to create native executable files (