src/ of a mid-1992 Emacs, version unknown

[SilverNexus]

Found this when going through some old 3 1/2" floppy disks; all the files were last modified June 16, 1992. I was not the one who put it there, so I have no context as to what it was used for or where it came from.
I think it is likely that this is version 18.58, 18.57, or 18.56, since some of the copyright dates in the sources go to 1991, but I'm not fully sure which it is.

Comparing to the 18.59 tarball that GNU has, it appears this is only the contents of the src/ folder of the version it is for. Not sure how useful it is just like that, but it's something.
GNU_Emacs_unknownversion.tar.gz

[dodona2]

there are some xemacs labels in the makefile.