IBM PC-DOS 7.0
Released in 1994 by IBM
For IBM PC compatibles

PC-DOS 7, AKA "IBM PC DOS 7.00, revision 0", adds the REXX
Programming language, XDF 1.86MB 3.5" floppy disk support, and
Stacker Disk compression.

This version was distributed on 3.5" media that used a special 1.8MB
"XDF" format. This format is not compatible with USB floppy drives or
most disk utilities.

To create working disks, you must run the Xdfcopy utility from DOS on
a 100% IBM PC compatible computer with a real 1.44mb floppy drive.