15 ILCS 310/10b.13

For layoffs by reason of lack of funds or work, abolition of a position or material change in duties or organization and for reemployment of employees so laid off, giving consideration in both layoffs and reemployment to seniority in service and performance record. The rules may provide for the reinstatement of sick leave and vacation days not liquidated in money upon the reemployment without regard to time of reemployment of any employee who is the subject of a layoff under these rules.