The GOLD Rules focus on fundamental principles and practices, and therefore are intended to apply to all space flight projects (and where applicable, associated ground projects) regardless of implementation approach or mission classification (except where explicitly noted). Whenever necessary, rules clarify requirements and expectations consistent with different mission classifications. Although not required, an a priori Mission Exceptions List (MEL) may be proposed at the start of a Program and/or Project, to highlight rules which may not apply to that mission. If a MEL is submitted and approved, waivers will not be required for exceptions covered by the MEL unless changes occur to the underlying basis for exception. For rules that include multiple elements (e.g., "test as you fly"), waivers and exceptions are valid for the specific elements indicated in a MEL or waiver and do not constitute a global approval to waive all elements of that rule. Other exceptions that arise during execution of the mission still require waivers, as appropriate. A MEL approved at the program level for multi project programs will be reviewed at key points in the program lifecycle (e.g. at the release of a new Announcement of Opportunity) to validate its applicability for new Projects within that program.