Rice Lake Motorola DS457 Laser Scanner - Manual (Page 415)

Glossary - 5
N
Nominal.
The exact (or ideal) intended value for a specified parameter. Tolerances are specified as positive and
negative deviations from this value.
Nominal Size.
Standard size for a bar code symbol. Most UPC/EAN codes are used over a range of magnifications
(e.g., from 0.80 to 2.00 of nominal).
NVM.
Non-Volatile Memory.
O
Open System Authentication.
Open System authentication is a null authentication algorithm.
P
Parameter.
A variable that can have different values assigned to it.
Percent Decode.
The average probability that a single scan of a bar code would result in a successful decode. In a
well-designed bar code scanning system, that probability should approach near 100%.
Print Contrast Signal (PCS).
Measurement of the contrast (brightness difference) between the bars and spaces of a
symbol. A minimum PCS value is needed for a bar code symbol to be scannable. PCS = (RL - RD) / RL, where RL
is the reflectance factor of the background and RD the reflectance factor of the dark bars.
Programming Mode.
The state in which a scanner is configured for parameter values. See
Scanning Mode
.
Q
Quiet Zone.
A clear space, containing no dark marks, which precedes the start character of a bar code symbol and
follows the stop character.
R
RAM.
Random Access Memory. Data in RAM can be accessed in random order, and quickly written and read.
Reflectance.
Amount of light returned from an illuminated surface.
Resolution.
The narrowest element dimension which is distinguished by a particular reading device or printed with a
particular device or method.
ROM.
Read-Only Memory. Data stored in ROM cannot be changed or removed.