Ah, it appears the keyboard command is limited to 128 bytes.

>Ken-
>
>>on key label f5 keyboard filetostr('Description.txt')
>
>Interesting idea. So I fiddled with it, and get "Key string is too long (Error 1257)." Of course, that might not be a problem for Nadya's application.
>
>>>on key label f5 keyboard filetostr('Description.txt')