It looks sane (by comparison) until you look into its semantics and hit this rabbit’s warren of weird-ass design decisions. And then compare how it is written in theory (like with full names of things) vs. in practice (executable line noise).

BANCStar looks very bad, but much of that, I suspect, is chiefly because it’s undocumented, making it hard to figure out what some of the magic numbers, etc. are. MUMPS is fully documented and still write-only (and only barely writeable!).