So, in 1983 I think the possible variants are 4.2BSD, SunOS 1.0, Xenix 3.0, SVR1. Someone in a sibling thread mentioned the kill line characters were already r

So, in 1983 I think the possible variants are 4.2BSD, SunOS 1.0, Xenix 3.0, SVR1. Someone in a sibling thread mentioned the kill line characters were already replaced around 2BSD. SVR1 had vi and ex, too. `lpr` is BSDian, I think, but maybe System V included that too as an alternative. It's hard to tell, really. At the time SVR1 was out and included fairly many bits of BSD in it, as did Xenix. The only thing I can really say is that SunOS is unlikely, since it was designed for workstations with video monitors from day 1 and the kill characters seem anachronistic since erasing was a standard feature in terminals already and default behavior in current BSD.