A step-down unit means a housing unit used for the progressive programming of an incarcerated individual with a violent or behavioral history that has led to long-term periods of segregated confinement in order to prepare him or her for return to general population or the community. Incarcerated individuals placed in a step-down unit shall be afforded out-of-cell time in the most congregate setting available and shall be provided the least restrictive environment necessary to maintain the safety and security of the facility.