The substitution of the characters of one alphabet for the corresponding characters of a different alphabet, usually accomplished on a character-by-character basis. Note 1: An example of alphabet transliteration is the substitution of the Roman letters a, b, and p for the Greek letters , , and , respectively. Note 2: Alphabet transliteration is reversible. Note 3: Alphabet transliteration often becomes necessary in telecommunications systems because of the different alphabets and codes used worldwide. Note 4: In alphabet transliteration, no consideration is given to the meaning of the characters or their combinations.