The Preamble to the Official Languages Act 1963,sort of defines what an ‘Official Language’ is.Here is how it goes:
An Act to provide for the languages which may be used for the official purposes of the Union, for transaction of business in Parliament, for Central and State Acts and for certain purposes in High Courts.
language used within government (e.g., courts, parliament, administration).
 Since “the means of expression of a people cannot be changed by any law”,
 the term “official language” does not typically refer to the language used by a people or country, but by its government.”
So its crystal clear that official language cannot be used for communication with the public,say Minister’s public speeches or Airlines public announcements. I wish some one brings this basic law to Honb’le President of India’s attention and makes him withdraw his consent immediately.Other wise the order is likely to be struck down by the Supreme Court of India ,on a petition filed in this regard by the 90 crore affected non-Hindi citizens of India.
Can President over-rule Parliamentary Law?
More over ,no Presidential order can over rule Parliamentary Law on Official Languages, which provides the following safeguards/assurance.
Provided further that where Hindi is used for purposes of communication between one State which has, adopted Hindi as its official language arid another State which has not adopted Hindi as its official language, such communication in Hindi shall be accompanied by a translation of the same in the English language :
Provided also that nothing in this sub-section shall be construed as preventing a State which has not adopted Hindi as its official language from using Hindi for purposes of communication with the Union or with a State which has adopted Hindi as its official language, or by agreement with any other State, and in such a case, it shall not be obligatory to use the English language for purposes of communication with that State.(2) Notwithstanding anything contained in sub-section (1), where Hindi or the English language is used for purposes of communication –
(i) Between one Ministry or department or office of the Central Government and another;
(ii) Between one Ministry or Department or office of the Central Government and any corporation or company owned or controlled by the Central Government or any office thereof;
(iii) Between any corporation or company owned or controlled by the Central Government or any office thereof and another, a translation of such communication in the English language or, as the case may be, in Hindi shall also be provided till such date as the staff of the concerned Ministry, Department, office or corporation or company aforesaid have acquired a working knowledge of Hindi.
(3) Notwithstanding anything contained in sub-section (1), both Hindi and the English language shall be used for –
(i) Resolutions, general orders, rules, notifications, administrative or other reports or press communiques issued or made by the Central Government or by a Ministry, Department or office thereof or by a corporation or company owned or controlled by the Central Government or by any office of such corporation or company;
(ii) Administrative and other reports and official papers laid before a House or the Houses of Parliament;
(iii) Contracts and agreements executed, and licences, permits, notices and forms of tender issued, by or on behalf of the Central Government or any Ministry, Department or office thereof or by a corporation or company owned or controlled by the Central Government or by any office of such corporation or company.
(4) Without prejudice to the provisions of sub-section (1) or sub-section (2) or sub-section (3), the Central Government may, by rules made under Section 8, provide for the language or languages to be used for the official purpose of the Union, including the working of any Ministry, Department, section or office, and in making such rules, due consideration shall be given to the quick and efficient disposal of the official business and the interests of the general public and in particular, the rules so made shall ensure that persons ‘serving in connection with the affairs of the Union and having proficiency either in Hindi or in the English language may function effectively and that they are not placed at a disadvantage on the ground that they do not have proficiency in both the languages.
(5) The provisions of clause (a) of sub-section (1), and the provisions of sub-section (2), sub¬section (3) and sub-section (4) shall remain in force until resolutions for the discontinuance of the use of the English language for the purposes mentioned therein have been passed by the Legislatures of all the States which have not adopted Hindi as their official language and until after considering the resolutions aforesaid, a resolution for such discontinuance has been passed by each House of Parliament.]”