Re: no `coding:' in file loc vars

> There won't be; coding cookies cause the developers more trouble
> than they're worth.  We get lots of bug reports when coding cookies
> fail due to pilot error.

This means that files originally created in (FSF) emacs are not
processed in xemacs properly.  How do emacs developers avoid such a
trouble?

> As for `set-auto-coding-function' I'm not sure what you want.

It is name of a built-in variable in (FSF) emacs.

> What would that do that "file-coding-system-alist" does not?

It would analyze (raw) file contents to decide coding system of file.
`file-coding-system-alist' specify file name check only.