How does government reservation policy work

Governments across India have their own list of Scheduled Castes or Dalits, Scheduled Tribes and backward and most backward castes. The central government too has its list.
(i)Students applying to educational institutions and those applying for posts in government are expected to furnish proof of their caste or tribe status, in the form of caste and tribe certificates.
(ii)Many government and educational institutions also ask for candidates to mention their caste/tribe status. If a particular Dalit caste or a certain tribe is on the government list, then a candidate from that caste or tribe can avail of the benefit of reservation.
(iii)For admission to colleges, especially to institutes of professional education, such as medical colleges, governments define a set of ‘cut-off’ marks. This means that not all Dalit and tribal candidates can qualify for admission, but only those who have done reasonably well and secured marks above the cut-off point.