I have some old business files and personal records scanned into the .xif format. I believe it stands for "Xerox Image Format" but Xerox sold to to Pagis who sold it to Nuance. No one seems to support it anymore.

Is there an open-source Image converter that will convert these files into .pdf or TIFF (xif is a four layer TIFF extension) or some other standard file?

Believe it or not, back in the day, Xerox seemed more permanent than Adobe so early digital archives often used Xerox Scanners and the .xif file type. Time changes everything.