I remember the a.out to elf transition because the first distro I used had Doom in its repos. When I installed it complained that a.out format wasn't supported

I remember the a.out to elf transition because the first distro I used had Doom in its repos. When I installed it complained that a.out format wasn't supported anymore. IIRC I tried kylix in 1999. It still requiring libc5 is strange. Well... those were not best inprise/borland days indeed.