I've heard of people using "MUG" but I have no idea what that actually is.
MUG! (MSDOS Utilities Graphical !nterface) is a IIgs NDA that allows MS-DOS
disks to be read, written and in many cases formatted. It translates line
endings between Apple format (<CR>) and DOS format (<CR><LF>).
It was originally written for use with 1.44Mb floppies using Apple's
SuperDrive, but it will work with any device that can actually read/write in
MS-DOS format. Typically these days it is used with Zip disks (or SyQuest
drives for those that still have them).
The original MS-DOS Utilities were (are!) command line MS-DOS-like utilities
for use with a command shell such as the ORCA, GNO/ME or ProSel command
shells.