Thanks, @musca.
Works only after modifying grub.cfg, but the recommended way via # update-grub or
# grub-mkconfig
, respectively, here generates the following disturbed lines (for all flavours):menuentry "siduction-16.1.0-patience-xfce-amd64-201612240021 (vmlinuz_4_9_0_towo.1_siduction_)" {
...
loopback loop /ISO/siduction-16.1.0-patience-xfce-amd64-201612240021.iso
linux (loop)/boot/vmlinuz_4_9_0_towo.1_siduction_ fromhd=UUID=d7b7f68a-0920-4441-88e2-10fae3477fd4 fromiso=/ISO/siduction-16.1.0-patience-xfce-amd64-201612240021.iso boot=fll lang=de_DE tz=Europe/Berlin quiet systemd.show_status=1 noeject
initrd (loop)/boot/initrd_4_9_0_towo.1_siduction_
}