Plan 9 from Bell Labs’s /usr/web/sources/contrib/btdn/src/chem/eth.p
.cstart # Ethamivan R: ring pointing right double 1,2 3,4 5,6 bond left from R ; OH bond -150 from R ; OCH3 bond right from R ; C double bond up ; O bond right from C ; N bond 45 ; C2H5 bond 135 from N ; C2H5 .cend