The Constitution of the Islamic Republic of Iran
Approved in 1980 - Revised in 1989
PART TWO - Language, writing, calendar, flag
The official language and writing of the people of Iran is the Farsi10. State correspondence, official documents and texts and school books must be written in that language: however, the use of local or tribal idioms is permitted, alongside Farsi, in the press and other mass media, and is permitted the teaching of the respective literatures in the schools.
Because Arabic is the language of the Qur'an, of Islamic science and teaching, and because Persian literature is deeply permeated by that language, its teaching must be taught in all classes and in all the curricula of study from the end of the elementary school until the end of middle school.
The years of the official calendar of the country are calculated starting from the emigration of the Prophet of Islam from Mecca11. Both the solar calendar and the lunar calendar are allowed12, however the state offices will use the solar calendar. The official public holiday of the week is Friday.
The official flag of Iran is green, white and red with the emblem of the Islamic Republic and the inscription "Allah'u Akbar" 13.