The term 'telegraphic E' is a type of Morse code used in telegraphy. It is composed of two parts: the letter 'D' (DIT) and the letter 'O' (DOT). DIT stands for 'dots in transmission' and DOT stands for 'dashes in transmission'. Together, they form the letter 'E', which is the most commonly used letter in the English language. The telegraphic E is used to send messages quickly and efficiently over long distances.