[Coco] Vigenère Cipher program for Coco

[Aaron Banerjee]

I was helping a friend with a "Geocaching" clue recently.  Part of it  
turned out to be a code snippet that was a modified Vigenere code.  I  
was thinking that this would be a fun thing to write in good ol' BASIC.

Out of curiosity, besides, Coco BASIC, are there any other BASICs  
still in existence that use line numbers, etc?  I'd like to make any  
program I would write as portable as possible while still being  
compatible with the Coco.

             - Aaron