The ql-users forum has recently been discussing boot files again. 25 years on from the launch of the QL one might think that the definitive word has been spoken on the correct construction of a SuperBasic/SBasic boot file. Not so. The enormous flexibility of the basic programming languages on QL systems and the differing characteristics of the existing hardware configurations and emulators means that confusion still reigns because there is no one set standard merely enormous flexibility to have a personally configured boot.
For example with original hardware and the JM rom, one of the commonest roms in use, one has to complete the installation of system extension libraries by resetting Superbasic through the loading of a secondary boot file for the launching of applications as otherwise the applications cannot see the extensions. For JS roms and above this is not essential. But there are still advantages in breaking down the boot into separate entities.