In some rental markets, access may be linked to conditions such as income level, gender or enrollment as a student. Some public housing may, for example, be purpose-built for low-income tenants, but allotted conditionally to specific groups, such as slum evictees or slum-dwellers who lost their houses in a fire. Some rental housing built by universities, charities or NGOs may be reserved for students, for women or for specific low-income groups