Step-Ladder Orientation 
When the barcode’s bars are positioned horizontally on the product, causing them to 
appear as a ladder. The ends of all bars will enter the scan window first. See par. 4.1. 
 
Symbol 
A combination of characters including start/stop and checksum characters, as 
required, that form a complete scannable barcode. 
 
Tilt 
Rotation around the Z axis. Used to describe the position of the barcode with respect 
to the laser scan line. See pars. 0 and 3.5. 
 
Trigger Signal 
A signal, typically provided by a photoelectric sensor or proximity switch, which 
informs the scanner of the presence of an object within its reading zone. 
 
UPC 
Acronym for Universal Product Code. The standard barcode type for retail food 
packaging in the United States. 
 
Visible Laser Diode 
A light source used in scanners to illuminate the barcode symbol.  Generates visible 
red light at wavelengths between 630 and 680 nm.  
 
 
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