double letter omitted incorrectly
    
single letter doubled incorrectly
    
letter omitted incorrectly
    
misspelling incorrectly contains this letter
    
letter has common misspelling occurring earlier in the alphabet
    
letter has common misspelling occurring later in the alphabet
    
letter sequence: begin with latest alphabet letter
    
letter sequence: begin with earliest alphabet letter
    
portion of word must be memorized by rote