edlin is clearly not a great editor. But it does have a couple of very handy virtues, at least in the form of the version written for FreeDOS by Gregory Pietsch and others.
To install, google say "freedos edlin" then unzip, run ./configure and then make, then make a link from the binary to your bin folder or just put the binary in there. If you want a man page, see my Wordpress (find a link to my Wordpress front page on the home page of this site).
1. The code is small (downloaded source zip is 214K) and the binary around 127K.
2. The code is very portable and compiles readily with few dependencies.
For example, I've compiled it on termux on my phone.