The tasks assigned to collecting agencies, or the requests made on collecting agencies not under the commander's control, will call for information (negative, if desired, as well as positive) as to specific indications of the enemy's action--past, present, or intended--and of the characteristics of the theater as related thereto. The indications to be sought for and reported are carefully determined by the commander in expectation that information obtained as to such matters will enable him to draw conclusions which will answer the questions posed by the essential elements of information. For example, essential elements of information, with corresponding indications, may be as follows: Essential Elements Indications 1. Will the enemy patrol the a. Presence or absence of enemy trade route from A to B? forces (number and types of vessels) between meridians--and--, as far north as--and as far south as--. b. Times enemy forces observed in area noted. c. Apparent activity of enemy forces so noted. 2. Will the enemy cover focal a. Presence or absence of enemy points M and N? forces (numbers and types of vessels) in (a specified area or areas). b. Times enemy forces observed in areas noted in a, above. c. Apparent activity of enemy so noted. d. Has M or N been prepared as a naval base; an air base for seaplanes, for land planes? Is M or N readily accessible to enemy battleships? What are the characteristics of the available entrances to sheltered anchorages? (Etc.) Another type of subsidiary problem which may call for a separate subsidiary plan relates to logistics (page 162). This problem is particularly applicable to the planning stage, because the contingencies which it involves can, to a considerable degree, be foreseen. In this case the situation which the commander usually desires to bring about is adequate freedom of action with respect to supply and related matters. He wishes to solve this problem so completely during the present step that a logistics plan, concurrently executed with his basic plan, will require minimum subsequent attention.