From the standpoint of theoretical precision, it might be said that the basic problem is abandoned when the conclusion is reached that its motivating task cannot be accomplished. It might also be said that the basic problem is abandoned when the conclusion is reached that the commander can in no way contribute toward the accomplishment of the motivating task. Practical experience indicates, however, that the basic estimate can profitably be utilized until the conclusion is reached that no contribution can be made to the purpose of the mission. At this point a new estimate, subsidiary to the basic estimate, necessarily begins. This view is confirmed, theoretically, by the fact that, at this point in the procedure, a radical change occurs with respect to the appropriate effect desired. In such circumstances, the commander concludes that he cannot contribute, in any degree, to the accomplishment of his immediate superior's general plan. The incentive for the solution of the subsidiary problem will therefore arise, on the basis thus adopted, when the commander has concluded that he cannot contribute to the accomplishment of his basic mission, and that he is under the necessity of evolving a new mission for himself. His basic Decision (see discussion, hereafter, of Section V of the Estimate Form) will reflect this conclusion and will thereby afford him a basis for the solution of his subsidiary problem. Problems of the foregoing nature, where the commander justifiably departs from his instructions, are not unusual during the first step. However, they are scarcely typical of that step so long as an organized chain of command is in effective operation. In the more usual case, the commander, at this point in his estimate, makes note of his selected course of action. Whether he selects a single course or a combination, the selection is thereafter known as the best course of action (singular). SECTION V THE DECISION In the final section of the Estimate the commander is concerned with a decision as to the selection of an objective or objectives determined by himself, for the attainment of the appropriate effect desired. This decision also indicates, in proper detail, the action to be taken for the attainment of the commander's selected objective. The decision reached at this point becomes the commander's general plan of action or provides the basis therefor. It is accordingly so important that when it has been formally stated in a basic problem it is thenceforth known as the Decision.