windowszones.res

Compiled resource file Reference

A .res file contains compiled resources for a Windows program. The resource compiler translates a resource script, .rc, into this binary form. The linker then puts the resources, for example dialogs, icons, and strings, into the executable. .NET tools use a similar format for managed resources. Build systems create these files automatically.

A file extension is only a part of the file name. It does not give a guarantee about the format or the content of a file. But on Windows, the extension selects the program that opens the file.