China DOS Union

Question: how should the uses of

DEVICEHIGH=EMM386.EXE RAM
and DEVICEHIGH=EMM386.EXE EMS
as well as DEVICEHIGH=EMM386.EXE NOEMS

be understood?
I checked some websites, and some places say the parameter after it is best set to RAM, while others say to use NOEMS.
On foreign websites, there are also different ways of loading EMM36.EXE

That depends on whether you prefer UMB memory more or EMS memory more. If you prefer UMB, use NOEMS; if you prefer EMS, use RAM.

DOS=HIGH,UMB,AUTO
DEVICE=C:\DOS\HIMEM.SYS /TESTMEM:OFF /Q
DEVICE=C:\TOOLS\UMBPCI.SYS /I=DC00-EFFF /F
DEVICE=C:\DOS\EMM386.EXE FRAME=NONE X=DC00-EFFF X=B800-C7FF I=CC00-DBFF I=B000-B7FF RAM M3 D=256 AUTO

XMS is controlled by HIMEM.SYS, EMS is controlled by EMM386.EXE, while UMB is controlled by UMBPCI.SYS and is also shared with EMM386.EXE. If you remove FRAME=NONE and change DC00-EFFF to D800-EFFF, and it doesn't hang, then the memory will be a bit larger...