What purpose do ELF files serve in the context of DC?

[Beefalo]

I know of ELF files for basically serving as executables on PS2. If you fire up uLaunchELF from a FMCB card, applications have the .elf extension.

I'm only now noticing them in a couple places with regard to Dreamcast. First, in the Plain Files of NesterDC 7.1+. Then in this list of public domain homebrew demos (each zip contains just a single ELF file - I extracted one as an example).

So yeah, what are ELF files for?

[megavolt85]

same as for PS2
DreamShell can boot ELF files