What is the [BOOT] folder and files 1-Boot-NoEmul.img, 1-Boot-NoEmul.img?

Question

ISO

I am a fan of digging through files and often in disk images I find the [BOOT] folder in which there are two files: 1-Boot-NoEmul.img and 2-Boot-NoEmul.img, or just Boot-NoEmul.img. What are these files for? Why are they important?

And another question: by what signs or how does the computer loader see that the inserted USB flash drive is an installation one? and is it possible to write / make / edit the files that are responsible for this so that, for example, the bootloader sees the flash drive on which some image is installed?

Answer 1

Read how to make a boot disk - and questions will disappear.
Check also the ventoy project, it might be what you are looking for.