THE NELSON MANDELA RULES 5 pertaining to him or her, subject to redactions authorized under domestic legislation, and shall be entitled to receive an official copy of such records upon his or her release. Rule 10 Prisoner file management systems shall also be used to generate reliable data about trends relating to and characteristics of the prison population, including occupancy rates, in order to create a basis for evidence-based decision-making. Separation of categories Rule 11 The different categories of prisoners shall be kept in separate institutions or parts of institutions, taking account of their sex, age, criminal record, the legal reason for their detention and the necessities of their treatment; thus: (a) Men and women shall so far as possible be detained in separate institutions; in an institution which receives both men and women, the whole of the premises allocated to women shall be entirely separate; (b) Untried prisoners shall be kept separate from convicted prisoners; (c) Persons imprisoned for debt and other civil prisoners shall be kept separate from persons imprisoned by reason of a criminal offence; (d) Young prisoners shall be kept separate from adults. Accommodation Rule 12 1. Where sleeping accommodation is in individual cells or rooms, each prisoner shall occupy by night a cell or room by himself or herself. If for special reasons, such as temporary overcrowding, it becomes necessary for the central prison administration to make an exception to this rule, it is not desirable to have two prisoners in a cell or room. 2. Where dormitories are used, they shall be occupied by prisoners carefully selected as being suitable to associate with one another in those conditions. There shall be regular supervision by night, in keeping with the nature of the prison. Rule 13 All accommodation provided for the use of prisoners and in particular all sleeping accommodation shall meet all requirements of health, due regard