STEVIE is perhaps my most noteworthy contribution to the Open Source movement, even though the phrase Open Source didn't exist way back in June of 1987 when I posted my little clone of the 'vi' editor to Usenet. STEVIE stood for:

    ST Editor for VI Enthusiasts

and although it was only a subset of real 'vi', it had a good implementation of the 'u' (undo) and '.' (repeat) commands. Here are the two parts of the original posting of STEVIE:

My implementation was usable and good enough for Tony Andrews to take and continue hacking on. A year later in June of 1988, Tony posted this 4-part version of STEVIE to Usenet: Since that time, the software has continuously evolved in the fine tradition of what we now call Open Source, to produce the widely-available and widely-ported editor now known as VIM. I was not involved after my initial development and posting to Usenet, and I didn't really keep track of it after a few years. (I was actually a bit disappointed when the 'u'ndo capability was broken by subsequent development, and was not fixed.)

When I recently discovered that VIM is the great-great-great-great-...-grandson of STEVIE, I was quite suprised and of course very pleased to know that my initial seed was so fruitful. And I was most pleased to see that they fixed the 'u'ndo command and even made it capable of 'infinite undo'.

I was even more surprised when I was contacted by Max Cantor who put together a Cheat Sheet for Vim that includes a portrait timeline featuring five of the contributors to Vim's long history. He included Ken Thompson (ed), Chuck Haley (ex), Bill Joy (vi), Tim Thompson (STEVIE), and Bram Moolenaar (vim). Wow, pretty cool!! You can see it here - https://thingsfittogether.com/ - and even order a copy, downloaded or printed.