Because there are only six letters in the letters(+30) group (letters 30-35,or U-Z),the other four positions in this group (36-39) are used to represent three symbols (dash, period, space) as well as the startstop character.
Because there are only six letters in the letters(+30) group (letters 30-35,or U-Z),the other four positions in this group (36-39) are used to represent three symbols (dash, period, space) as well as the startstop character.