The keyword refers to Update 1.001. Here is why this specific version is legendary:

Version 1.001 was the final official patch released for Yuri's Revenge. While some digital versions (like those from the EA App or Steam) might display different version numbers or include modified executables, the community tools are built specifically to hook into the 1.001 retail/Origin-based structure. Where to Download

Gamemd.exe 1.001: The Essential Patch for Yuri’s Revenge If you are trying to run modern mods for Command & Conquer: Yuri’s Revenge

When downloading and using Gamemd.exe 1.001, you might encounter some issues. Here are some common problems and their solutions:

Yes, but only with the CNC-DDraw wrapper. Windows 11 removed old DirectDraw hardware acceleration.