How to save a CAS program

[parisse]

But then why make a difference, what about being able to save any CAS function individually in the connectivity kit ? In fact, the other way is the most interesting, import a CAS function written with a PC keyboard to the Prime. What I would like to do (and probably most users who need a CAS program) is: write/debug/test my function inside Xcas on the PC, then run it on the Prime. I can copy/paste from the PC to the Prime emulator but not to the Prime. I can save the program in Xcas as text as progname.cas, but I can not send it to the Prime.