Offenders are ordinarily required to maintain law-abiding behavior, and may be ordered to refrain from possession of firearms, remain employed or participate in an educational program, abide a curfew, live at a directed place, obey the orders of the probation officer, or not . The probationer might be ordered as well to refrain from contact with the victims (such as a former partner in a domestic violence case), with potential victims of similar crimes (such as minors, if the instant offense involves child sexual abuse), or with known criminals, particularly co-defendants. Additionally, offenders can be subject to refrain from use or possession of alcohol and drugs and may be ordered to submit alcohol/drug tests or participate in alcohol/drug psychological treatment. Offenders on probation might be fitted with an electronic tag (or monitor), which signals their movement to officials. Some courts permit defendants of limited means to perform community service in order to pay off their probation fines.