vcursor.el has been part of Gnu Emacs since version 21.2.
It is inspired by an editing mode provided by the BBC Micro (c. 1981), providing a virtual cursor which can be moved independently of point and used as a source of text to copy and paste.
In fact, it is very easy to pick up the basic idea if you try it:
(setq vcursor-key-bindings 't) ;; enable default bindings to try it out (load "vcursor")
Then try C-S-up, C-S-left, C-S-insert to see the effect.
After that you’ll probably want to read the instructions in the file.
Back in the days of the BBC Micro, this was the best editing mode available. But in the Emacs world does anyone find it useful for everyday editing?