9-10. The chief of staff (COS) (executive officer [XO]) is a key participant in the MDMP. The COS (XO) manages and coordinates the staff’s work and provides quality control during the MDMP. To effectively supervise the entire process, this officer has to clearly understand the commander’s intent and guidance. The COS (XO) provides timelines to the staff, establishes briefing times and locations, and provides any instructions necessary to complete the plan.