Past Discipline or Warning. With the exception of suspension of employment, notices pertaining to discipline or warnings will be maintained on an employee’s personnel file for a period not exceeding eighteen (18) months from the date it was issued, provided there has not been further infraction. Notices pertaining to suspension of employment will be maintained on an employee’s personnel file for a period not exceeding twenty four (24) months from the date it was issued, provided there has not been further infraction.