On a BIOS PC, most folks use Grub4DOS to boot ISO images. But how to boot them on UEFI PC, especially without Legacy CSM Mode, since Grub4DOS doesn't support UEFI? Taking a popular Acronis True Image Home (ATIH2014) ISO as an example (either Linux or WinPE 5.0 based, or better BOTH), can someone explain, how to boot an ISO on UEFI Windows 8.1 PC? I found one example of booting seemingly WinPE-based UEFI ATIH2014 (release unknown) by Grub2. That didn't work for me - couldn't find dat8.dat and dat9.dat files in Boot.bif image extracted by UltraISO from the mounted ATIH2014 ISO boot sector. I couldn't also mount any *.img files from Floppy Image written on the ISO's CD track due to unknown *.img filesystem. Its unclear, why boot images extracted by ISOBuster were different from those extracted by UltraISO from the same ISO? As well, how an average user can derive similar grub.cfg menu section - based on what miracle vision? Any background explanation or more generalized logical approach would be handy... Also, how GOP-only HW support plays into this?