It is striking that tone symbols and some vowels are included several times in the table. Why? They are located at different heights in the character set, so that a suitably equipped program can construct the signs more tightly together. Example:

A consonant without a vowel, but with a tone symbol is usually written as: At least the keyboard generates the default code for that. An intelligent program could recognize, however, that the reserved space for a vowel is not required in this case, and replace the tone mark with a lower position for displaying and printing:

The replacement should not take place if the consonant has a vowel already: otherwise it will result in .