(a) The trial court, in its discretion, may hold a pretrial conference, with trial counsel present, to consider such matters as will promote a fair and expeditious trial. The accused shall be present unless he waives his right to appear.(b) At the conclusion of the conference, a pretrial order shall set out the matters ruled upon. Any stipulations made shall be signed by counsel, approved by the court and filed, and shall be binding upon the parties at trial, on appeal, and in postconviction proceedings unless set aside or modified by the court.