P
Parity Bit /
Parity Check /
PCS /
PLU /
POS /
Prefix
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Parity Bit
A binary check digit that is inserted into
an array of digits to make the arithmetic sum of all digits, including
the check digit, always odd or always even. The parity bit is sent at the
same time as data bits from the external device to central memory.
Parity Check
An error checking procedure in which the number of 1s must always be the
same (either odd or even) for each group of bits transmitted without error.
In many barcode except
EAN,
black bar module must be
odd or even by adding a parity bit.
PCS
Print Contrast Signal.
A measurement of the ratio of the reflectiveness between the bars and spaces
of a symbol, commonly expressed as a percent. PCS is calculated as:
PCS = (Rw - Rb) / Rw
Rw = reflectance of the white bar
Rb = reflectance of the black bar
The minimum value of PCS differs by the value of Rw (reflection rate in this case is against red light at
660 nanometer wave length.)
(See MRD)
PLU
Price Look Up.
The process by which a bar coded item number is decoded, its price looked
up in a database, and the price information is sent back to the scanning
location. The sales prices are entered into the store controller or computer,
and
when the product information
is scanned at the POS Register,
the Price information is
Looked Up from the store computer database.
(See NON-PLU)
POS
Point of Sale. The term refers to two types of terminals
used in retail stores: (a) A terminal with magnetic stripe reader, keyboard,
display and auto dialer modem, connected to the telephone network and used
for on-line credit/debit authorization; (b) A more complex terminal including
the
above features less the modem, connected to a host computer, which handles
all transaction processing including item price look-up (PLU), data collection,
and credit/debit authorization.
Prefix
A prefix originally means a character or group of characters added in front
of a string of characters. In the case of the EAN
symbol,
an extra digit is added to the 12-digits. The prefix is expressed with
the combination of odd / even parities
by the six left-most characters.
The combinations of O(dd) or E(ven) for expressing the prefix is as follows:
0 = O - O - O - O - O - O
1 = O - O - E - O - E - E
2 = O - O - E - E - O - E
3 = O - O - E - E - E - O
4 = O - E - O - O - E - E
5 = O - E - E - O - O - E
6 = O - E - E - E - O - O
7 = O - E - O - E - O - E
8 = O - E - O - E - E - O
9 = O - E - E - O - E - O
Parity Bit /
Parity Check /
PCS /
PLU /
POS /
Prefix
A B C
D E F
G H I
J K L
M N O
P Q R
S T U
V W X
Y Z -
Back to Glossary Index -
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