Okla. Stat. tit. 57, § 350

A. Every person, hereinafter referred to as "convict", who has been or who in the future may be sentenced to imprisonment in any state penal institution shall, in addition to any other deductions provided for by law, be entitled to a deduction from his sentence for all time during which he has been or may be on parole. The provisions of this section are hereby declared to be both retroactive and prospective, and to apply to convicts who are on parole on the effective date of this act as well as to convicts who may be paroled thereafter; and shall at the discretion of the paroling authority apply to time on a parole which has been or shall be revoked. B. Beginning November 1, 1987, the paroling authority also shall have the discretion to revoke all or any portion of the parole.