Glossary - 7

SPP. Serial Port Profile.
Start/Stop Character. A pattern of bars and spaces that provides the scanner with start and stop reading instructions and
scanning direction. The start and stop characters are n ormally to the left and right margins of a horizontal co de.
Substrate. A foundation material on which a substance or image is placed.
Symbol. A scannable unit that encodes data within th e conventions of a certain symbology, usually includi ng start/stop
characters, quiet zones, data characters and check characte rs.
Symbol Aspect Ratio. The ratio of symbol height to symbol width.
Symbol Height. The distance between the outside edges of the quiet zone s of the first row and the last row.
Symbol Length. Length of symbol measured from the beginning of the quiet zone (margin) adjacent to the start charac ter
to the end of the quiet zone (margin) adjacent to a stop chara cter.
Symbology. The structural rules and conven tions for representing data within a particular bar code ty pe (e.g. UPC/EAN,
Code 39, PDF417, etc.).
T
Tolerance. Allowable deviation from the nominal bar or sp ace width.
U
UPC. Universal Product Code. A relatively complex numeric sy mbology. Each character consists of two bars and two
spaces, each of which is any of four widths. The standard sy mbology for retail food packages in the United States.
V
Visible Laser Diode (VLD). A solid state device which produces visible laser l ight.