the most immediate and serious threat to the supported unit. Two other NATO terms also need definition: Neutralization fire: delivered to render a target temporarily ineffective or unusable; and Suppression fire: that degrades the performance of a target below the level needed to fulfill its mission. Suppression is usually only effective for the duration of the fire. The tactical purposes also include various "mission verbs", a rapidly expanding subject with the modern concept of "effects based operations".Targeting is the process of selecting target and matching the appropriate response to them taking account of operational requirements and capabilities. It requires consideration of the type of fire support required and the extent of coordination with the supported arm. It involves decisions about: what effects are required, for example, neutralization or suppression; the proximity of and risks to own troops or non-combatants; what types of munitions, including their fuzing, are to be used and in what quantities; when the targets should be attacked and possibly for how long; what methods should be used, for example, converged or distributed, whether adjustment is permissible or surprise essential, the need for special procedures such as precision or danger close how many fire units are needed and which ones they should be from those that are available (in range, with the required munitions type and quantity, not allotted to another target, have the most suitable line of fire if there is a risk to own troops or non-combatants); The targeting process is the key aspect of tactical fire control. Depending on the circumstances and national procedures it may all be undertaken in one place or may be distributed. In armies practicing control from the front, most of the process may be undertaken by a forward observer or other target acquirer. This is particularly the case for a smaller target requiring only a few fire units. The extent to which the process is formal or informal and makes use of computer based systems, documented norms or experience and judgement also varies widely armies and other circumstances. Surprise may be essential or irrelevant. It depends on what effects are required and whether or not the target is likely to move or quickly improve its protective posture. During World War II UK researchers concluded that for impact fuzed munitions the relative risk were as follows: men standing – 1 men lying – 1/3 men firing from trenches – 1/15–1/50 men