I think he meant you can put them on one line...

CASE "a": letter$ = "z"

'You might also consider something like the following (would save a lot of typing).

source$ = "abcdefg"
coded$ = "cdefghi"

TestCharacter$ = "e"
letter$ = MID$(coded$, INSTR(source$, TestCharacter$), 1)
PRINT letter$

'The fifth character in the source string ("e") corresponds to the fifth character in the coded string ("g").

-Bob