For the purposes of this chapter, “included nonrepresented employees” shall mean the members of the Board of Supervisors, the Assessor, the Auditor, the Clerk-Recorder, the District Attorney, the Human Services Director, the Chief Probation Officer, Public Works Director, the Sheriff/Coroner, the Transportation and Planning Director, the Treasurer/Tax Collector and any assistant department heads or deputy director positions as may from time to time be established by the Board of Supervisors.