Invalid string encountered in LETTERS declaration.
#3029 Compile-time error
Invalid string encountered in LETTERS declaration.
Additional Information
The lower-case string has 'X' characters in it, but the
upper-case string 'Y' has 'Z' characters.
or
The format item '%n' cannot appear inside the letters rule.
Recovery
Compilation continues but no compiled source code file will be saved.
Explanation
The letters declaration takes either one string of any size
or two strings of the same size after processing. Processing involves
changing all the %...# character codes and allowed format items to the
single characters they represent. The following format items are not
allowed: '%a', '%b', '%c', '%d', '%g', '%i', '%q', '%v', '%x', '%y',
'%[', '%]', or '%/'.