Listing:

    1  MODULE VBadByte;
    2  VAR c : ARRAY [1 .. 5] OF CHAR; ExitCode : INTEGER;
    3  PROCEDURE Bump(VAR x : CHAR);
    4  BEGIN
    5    x := "z"
    6  END Bump;
    7  BEGIN
    8    c[1] := "a";
    9    Bump(c[1]);
*****            ^ invalid procedure call
   10    ExitCode := 0
   11  END VBadByte.

    1 error