[bitcrazed]

IFSHLP.SYS was originally created during the implementation of OS/2 1.2, and later released in Windows 3.11 running on 32-bit 386 Enhanced Mode.

Its job was to provide 32-bit file access (bypassing 16-bit DOS file IO mechanisms), and ensuring nothing else on the system could intercept INT 21h calls.

ME didn't depend on MS-DOS (though it did provide support for running MS-DOS apps).