MIL-HDBK-1908 Definitions of Human Factors TermsThis handbook defines terms frequently used in human factors standardization documents by providing common meanings of such terms to ensure that they will be interpreted consistently and in the manner intended.

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MIL-HDBK-1908B

Local tracks dsi. Tracks generated by the co-located sensor(s) upon which the air defense system relies to acquire targets, e.g., tracks obtained from the system's own radar. Also known as "ownership tracks".

Logistic Support Analysis (LSA) acq. The selective application of scientific and engineering efforts undertaken during the acquisition process, as part of the system engineering and design processes to assist in complying with supportability and other Integrated Logistics Support (ILS) objectives. ILS is a management process to facilitate development and integration of logistics support

elements to acquire, field and support a system. These elements include: design, maintenance planning, manpower and personnel, supply support, support equipment, training, packaging and handling, transport, standardization and interoperability.

Lowercase letters uci. The "small" letters. Letters that are not capitalized.

Luminance gen. The amount of light flux (power) per unit area per solid angle (steradian) emitted or reflected from a surface. The metric unit for luminance is candelas per square meter or lumens per steradian per square meter.

Luminance contrast gen. The contrast between a figure and its background equals the difference between the higher luminance (Lmax) and the lower luminance (Lmin) divided by the lower luminance (Lmin), i.e.,

C = Lmax - Lmin

Lmin

Related contrast formulae are as follows:

Lmax	Lmin	Luminance Contrast	Luminance Contrast (Alt)	Modulation Contrast	Contrast Ratio
Lmax	Lmin	Lmax - Lmin Lmin	Lmax - Lmin Lmax	Lmax - Lmin Lmax + Lmin	Lmax Lmin
100	50	1.0	0.50	0.33	2.0
100	25	3.0	0.75	0.60	4.0
100	10	9.0	0.90	0.82	10.0

For display applications: Lmax is the total luminance of the area with the higher luminance, including any background or reflected light, as measured in the specified lighting conditions; Lmin is the luminance of the area with the lower luminance, as measured under the specified lighting

conditions, including any reflected light and any stray display emissions.

Luminance ratio (LR) gen. The ratio of the target, subject, or symbol luminance to the surrounding field or background luminance. For projection systems, the luminance ratio is equal to the light output of a projector (measured with no film in the projector) reflected off the screen (image luminance) divided by all the light falling on the screen (measured from the greatest viewing angle) other than that actually forming the image (nonimage or background), i.e., LR = L /Ln,

where L = Image or subject luminance and Ln = Nonimage or background luminance.

Macro uci. The capability to allow the user to assign a single name or function key to a defined series of commands for use with subsequent command entry. Sometimes called "smart key" or "script." Examples of use are storage of addresses or signature blocks that are frequently used. Usually initiated through use of a function key.