4. The computer-implemented method of claim 3 , wherein a first placeholder symbol is used to represent a missing consonant in each two-set token comprising zero consonants.
4. The computer-implemented method of claim 3 , wherein a first placeholder symbol is used to represent a missing consonant in each two-set token comprising zero consonants. 5. The computer-implemented method of claim 4 , wherein a second placeholder symbol is used to represent a missing vowel in each two-set token comprising zero vowels.