Section 4 in The Official Languages (Use For Official Purposes Of The Union) Rules, 1976
4. Communications between Central Government Offices .-Communications--
(a)between one Ministry or Department of the Central Government and another may be in Hindi or in English;(b)between one Ministry or Department of the Central Government and attached or subordinate offices situated in Region "A" shall be in Hindi and in such proportion as the Central Government may, having regard to the number of persons having a working knowledge of Hindi in such offices, the facilities for sending communications in Hindi and matters incidental thereto, determine from time to time;(c)between Central Government offices situated in Region "A" other than those specified in clause (a) or clause (b), shall be in Hindi;(d)between Central Government offices situated in Region "A" and offices in Region "B" or Region "C" may be in Hindi or in English:Provided that these communications shall be in Hindi in such proportion as the Central Government may, having regard to the number of persons having working knowledge of Hindi in such offices, the facilities for sending communications in Hindi and matters incidental thereto, determine from time to time;(e)between Central Government offices situated in Region "B" or Region "C" may be in Hindi or English:Provided that these communications shall be in Hindi in such proportion as the Central Government may, having regard to the number of persons having working knowledge of Hindi in such offices the facilities for sending communication in Hindi and matters incidental thereto, determine from time to time:Provided that a translation of such communication in the other language shall:--(i)where the communication is addressed to an office in Region "A" or Region "B" be provided, if necessary, at the receiving end;(ii)where the communication is addressed to an office in Region "C" be provided alongwith such communication:Provided further that no such translation in the other language shall be required to be provided if the communication is addressed to a notified office.
