Gian Giorgio Trissino (1478–1550)
en.wikipedia.org/wiki/Gian_Giorgio_Trissino
ru.wikipedia.org/wiki/%D0%A2%D1%80%D0%B8...80%D0%B4%D0%B6%D0%BE
«Италия, освобожденная от готов»
Обширная, написанная белым стихом поэма «L’Italia liberata dai Gothi» (1548), задуманная как программный памятник нового итальянского гуманизма, не удалась и была холодно встречена.
Триссино в «Послании о буквах, вновь добавленных к итальянскому языку» (1524) предлагает реформу итальянской орфографии;
The proposition was ignored, except for the last point, which brought to the modern distinction U vs. V and I vs. J, which eventually caught up also for other European languages.
was the first to explicitly distinguish I and J as representing separate sounds, in his Ɛpistola del Trissino de le lettere nuωvamente aggiunte ne la lingua italiana ("Trissino's epistle about the letters recently added in the Italian language") of 1524.<4> Originally, 'I' and 'J' were different shapes for the same letter, both equally representing /i/, /iː/, and /j/; but Romance languages developed new sounds (from former /j/ and /ɡ/) that came to be represented as 'I' and 'J'; therefore, English J, acquired from the French J, has a sound value quite different from /j/ (which represents the initial sound in the English word "yet").
а вот про употребление в цифрах римских:
The letter 'J' originated as a swash character, used for the letter 'i' at the end of Roman numerals when following another 'i', as in 'xxiij' instead of 'xxiii' for the Roman numeral representing 23
