China DOS Union

Brother Wengier mentioned in point 20 of the main features:
The DOS system boot file IO.SYS was also streamlined by me, saving as much as about 100KB of disk space, yet without reducing the system's functionality in the slightest; instead it greatly speeds up booting and improves system compatibility and practicality.
How is this achieved?

I think the io.sys in winme is relatively small.

Wengier removed the Win98 logo from io.sys, so it is relatively smaller.
As for why WinME's io.sys is so small, it's because it has been compressed!
I really don't know when MSDOS7.1's io.sys can also be compressed like WinME's!

Thanks!
Could you be a bit more specific?
What tool did Brother Wengier use? How was it done?

I used tools such as EDIT and PCTOOLS to do it. As for WinME's (DOS8) IO.SYS, although it is also small, its compatibility is not good, because MS not only compressed it, but also removed some DOS functions, so it is relatively small.