These include over 400 different varieties of UNIX, VMS configurations on VAX and Alpha dating back to VMS 4-point-something, Data General AOS/VS, Stratus VOS, OS-9/68000, the Commodore Amiga, and more. Plus Windows 95/98/NT/2000 and OS/2, where Kermit 95 supports exactly the same script language.
And C-Kermit's script programming language is about 90% compatible with that of MS-DOS Kermit, which runs on DOS and Microsoft Windows. With some care, Kermit script programs can easily be written to run under both C-Kermit and MS-DOS Kermit.
That's portability.