It is needed when dealing with setFilePointerEx.

The definition seems to be

#define INVALID_SET_FILE_POINTER ((DWORD)-1)

which translates to 4294967295. That's also why I found it confusing that setFilePointerEx returns LARGE_INTEGER, although the documentation says it should be DWORD: https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-setfilepointer