Rockwell Automation 2755-L7, -L9 Scanners - Manual (Page 45)

Glossary
G–7
OCR–B
An abbreviation commonly applied to the character set contained in ANSI
Standard x3.49–1975.
off–line
Refers to devices that operate independently of a central processing unit.
on–line
An operation in which peripheral devices are connected directly to the
computer central processor unit.
opacity
1) The property of paper that minimizes the show through of printing from
the back side or the next sheet.
2) The ratio of the paper reflectance with a black backing to the paper
reflectance with a white backing.
scanning range
The sum of the scan head’s optical throw and depth–of–field.
optical throw
The distance from the face of the scanning device to the center of the depth
of field.
orientation
The alignment of bars and spaces to the scanner. Often referred to as vertical
(picket fence) or horizontal (ladder).
P
parallel beam
A beam of light that is optically controlled so the light travels in a parallel
path. Generally used when the object is larger than the lens diameter.
parallel code
A code configuration that is optically scanned in its entirety at one time.
Since all codes marks are read simultaneously, the code can move pass the
reader in either direction.
parity bar, parity bit, parity module
A parity bit is added to a binary array to make the sum of all the bits always
odd or always even; a fundamental check.
permanent code
A code which is indefinitely reused in a bar code application.
picket fence orientation
A bar code or symbol presented in such a manner that its overall length
dimension is parallel to the horizon. The bars look like a picket fence.