But then Triplett's definition for systems programming is not some ISO standard. In lot of companies I have seen they call their large internal applications dev

But then Triplett's definition for systems programming is not some ISO standard. In lot of companies I have seen they call their large internal applications development as systems programing. Also compilers, runtimes, GCs, databases, cloud schedulers (Kubernetes etc) are also not 'apps' could fit in systems programing definition.