We see that while article l 5(4) contemplates "special provision for the advancement of any socially and educationally backward classes of citizens or for the Scheduled Castes and the Scheduled Tribes", article 16(4) speaks of 'provision for the reservation of appointments or posts in favour of any backward class of citizens which, in the opinion of the State is not adequately represented in services under the State" Now, it is not suggested that the socially and educationally backward classes of citizens and the Scheduled Castes and the Scheduled Tribes from whom special provision for advancement is contemplated by Art 15(4) are distinct and separate from the backward classes of citizens who are adequately represents in the services under the State for whom reservation of posts and appointments is contemplated by article 16(4). 'The backward classes of citizens ' referred to in article 16(4), despite the short description, are the same 404 as the socially and educationally backward classes of citizens and the A scheduled castes and the Scheduled Tribe ', 90 fully described in article 15(4): Vide Trilokinath Tiku vs State of Jammu and Kashmir and other cases.