Section 804 - Good behavior allowances against definite sentences1. Every person confined in an institution serving a definite sentence of imprisonment may receive time allowances as discretionary reductions of the term of his sentence not to exceed in the aggregate one-third of the term imposed by the court. Such allowances may be granted for good behavior and efficient and willing performance of duties assigned or progress and achievement in an assigned treatment program, and may be withheld, forfeited or cancelled in whole or in part for bad behavior, violation of institutional rules or failure to perform properly in the duties or program assigned.2. If a person is serving more than one sentence, the authorized allowances may be granted separately against the term of each sentence or, where consecutive sentences are involved, against the aggregate term. Allowances based upon sentences of less than one month may be granted, and in such case the maximum allowance shall be one day for every three days of the sentence. In no case, however, shall the total of all allowances granted to any such person exceed one-third of the time he would be required to serve, computed without regard to this section.3. No person shall have the right to demand or require the allowances authorized by this section. The decision of the sheriff, superintendent, warden or other person in charge of the institution, or where such institution is under the jurisdiction of a county or city department the decision of the head of such department, as to the granting, withholding, forfeiture, cancellation or restoration of such allowances shall be final and shall not be reviewable if made in accordance with law.4. A person who has earned a reduction of sentence pursuant to this section and who has been conditionally released under subdivision two of section 70.40 of the penal law shall not forfeit such reduction by reason of conduct causing his return to the institution. Provided, nevertheless, that such reduction may be forfeited by reason of subsequent conduct while serving the remainder of his term.5. The state commission of correction shall promulgate record keeping rules and regulations for the granting, withholding, forfeiture, cancellation and restoration of allowances authorized by this section.6. Notwithstanding anything to the contrary in this section, in any case where a person is serving a definite sentence in an institution under the jurisdiction of the state department of corrections and community supervision, subdivisions three and four of section eight hundred three of this chapter shall apply.7. Upon commencement of any definite sentence the provisions of this section shall be furnished to the person serving the sentence and the meaning of same shall be fully explained to him by an officer designated in the regulation to perform such duty.