Hand Held Products Quick Check PC600 User Manual page 55

from several directions. Light sources for bar code reading equipment are
typically infrared (900 nanometers peak), visible red (630 to 720 nanometers),
and incandescent (400 to 900 nanometers). The source wavelength of He-Ne
laser light is precisely 632.8 nanometers.
linear symbol: A one-dimensional bar code symbol. An array (linear sequence)
of rectangular bars and spaces that are arranged in a predetermined pattern
following specific rules to represent elements of data that are referred to as
characters. A linear symbol typically contains a leading quiet zone, start
character, symbol character(s) including a check character (if any), stop
character, and a trailing quiet zone, for example, Code 39 and Code 128.
Compare to "two-dimensional symbol".
lithography: A printing process in which both the image and non-image areas
are on the same plane. It is based on the principle that oil (ink) and water do not
mix. The image is first transferred to a rubber blanket cylinder and then to paper.
machine-readable: That characteristic of automatic data capture media that
permits the direct transfer of information from a medium to a data processing
system, without operator intervention. Bar code and two dimensional symbols,
magnetic stripe, smart cards, touch memories, radio-frequency identification,
biometrics. and optical character recognition are technologies of machine
reading. The data is usually contained in pre-defined locations (fields) within a
data stream. This data can be interpreted by a computer program.
machine-readable symbol: An optically read machine readable media, such as
a bar code, two-dimensional, or optical character recognition (OCR) symbols.
magnification factor: The constant multiplier applied to the nominal dimensions
of a bar code symbol to obtain the actual dimensions at which it must be
produced.
margins: The clear area above, below, and on either side of the bar code, two-
dimensional, or OCR symbol to be read.
maximum reading distance: The distance from the reading device to the end
of the depth of field.
maximum reflectance (R max ): The reflectance of the lightest bar in an entire
scan profile.
Message length: The number of characters encoded in the bar code symbol.
minimum edge contrast (EC min ): The smallest edge contrast in a scan
reflectance profile.
minimum reflectance (R min ): The smallest reflectance value in a scan
reflectance profile.
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