runwin8.g4b is correct. It is used for Win8, Win10, SVR2012 and SVR2016. Please ensure you have set MFOLDER to point to the folder that contains your ISO file and your .XML and .KEY files.
# Win10 Example
# use this for Win8/8.1/SVR2012/WIN10 ISOs - all use RunWin8.g4b
iftitle [if exist /_ISO/WINDOWS/Win10/Win10_64.iso] Install Win10 64-bit \nInstall from the ISO
set MFOLDER=/_ISO/WINDOWS/WIN10
set ISO=Win10_64.iso
# to choose XML or Product Key do not set XML variable to anything
set XML=
# OR - Specify XML file name (must be in MFOLDER folder) e.g. Win10\ has\ spaces\ in\ name.xml - DO NOT USE FULL PATH!
# set XML=NO\ KEY\ (choose\ a\ version\ to\ install).xml
# Do not change next line...
/%grub%/RunWin8.g4b %MFOLDER% %XML%
boot
Topic: Easy2Boot
Date 03/12/2017
By SteveSi
Subject Re: Small problem adding Windows 10 to main menu
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