Glossary - 11
ignored, because there is no time to re transmit. If UDP is used and a reliab le delivery is required, packet sequence
checking and error notification must be written into the applications.
UPC. Universal Product Code. A relatively complex numeric symbology. Each character consists of two bars and two
spaces, each of which is any of four widths. The standard symbology for retail food packages in the United States.
V
Visible Laser Diode (VLD). A solid state device which produces visible laser light.
W
Warm Boot. A warm boot restarts the mobile computer by closing all running programs. All data that is not saved to
flash memory is lost.