Inmates are assigned to local or national prisons, depending on the length of their sentences. During incarceration, emphasis is placed on inmates' maintaining close ties with society through sojourns (often for treatment or training) and work and study releases. Probation, an alternative to imprisonment, involves substantial intervention under the supervision of a probation officer or lay supervisor. Conditional releases, granted to inmates serving 2 or more years, are determined by the Correctional Services Board. Those serving less than 2 years are released on half time. Another option, day fines, is based on the seriousness of the offense and the offender's economic circumstances. In addition, conditional sentences, entailing no imprisonment, may be ordered for those who do not require further support or control to prevent further criminality. Debate over the half-time conditional release may result in future reforms in the system.