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1. The volume of influence of a physical phenomenon, expressed vectorially. 2. On a data medium or in storage, a specified area used for a particular class of data, e.g. , a group of character positions used to enter or display wage rates on a screen. 3. Defined logical data that are part of a record. 4. The elementary unit of a record that may contain a data item, a data aggregate, a pointer, or a link. 5. In an interlaced, raster-scanned video display, a partial frame, consisting of every nth scanning line of a complete frame, where n is an integer equal to the number of fields (usually two) in a complete frame. Note 1: For example, in the National Television Standards Committee (NTSC) television specification used in the United States, a single frame is composed of two fields, each of which has half the number xxof scanning lines in a complete frame. The scanning lines of a field are separated by twice the space between the scanning lines in the full frame. The two fields are interlaced, i.e. , a complete frame consists of the following traces, which are listed in the order of their appearance in the complete frame, but not the order in which scanning occurs: the first line of the first field, the first line of the second field, the second line of the first field, the second line of the second field, the third line of the first field, the third line of the second field, etc. , until completion of the full frame. The fields are scanned alternately, one complete field at a time. Thus, the flicker rate of the display is perceived by the eye to be twice as fast as that which would result if the complete frame were to be scanned in line-by-line order. Note 2 : Not all scanning lines are necessarily applied to user information, i.e. , the graphic display. Certain scanning lines, not seen under ordinary viewing conditions, are often used for transmitting test signals that indicate the quality of the displayed video.