sentences:  Article 153 of the law mandates that health insurance be compulsory, that health providers must have administrative autonomy, and that health users must have free choice of health providers.The System for the Selection of Beneficiaries for Social Programs (El Sistema de Seleccion de Beneficiarios para Programas Sociales), the national system of identification of beneficiaries for social subsidy, classifies the people according to the residential properties that should receive public services.All mayors should do the stratification of residential properties of their municipality or district.