A timetable imposes a discipline which is helpful in several respects: (1) it encourages all participants to contribute in a timely manner; (2) it helps avoid delay imposed by a desire to go on improving a draft which may already be good enough; (3) it gives warning of events that may interfere with the preparation of the NEHAP such as holiday seasons, Parliamentary recess; and (4) it may indicate the need for additional resources. Within a timetable it is helpful to identify certain key events as milestones which are critical for timely completion of the whole project and which, if missed, might necessitate reconsideration of the remaining timetable or the resources devoted to it.