Glossary - 8 MC55 User Guide

TFTP. (Trivial File Transfer Protocol) A version of the TCP/IP FTP (File T ransfer Protocol) protocol that has no directory or
password capability. It is the protocol used for upgrading firmware, do wnloading software and remote booting of diskless
devices.
Tolerance. Allowable deviation from the nominal bar or space width.
Transmission Control Protocol/Internet Protocol. See TCP/IP.
Trivial File Transfer Protocol. See TFTP.
U
UDP. User Datagram Protocol. A protocol within the IP protocol suite that is use d in place of TCP when a reliable delivery
is not required. For example, UDP is used for real-time audio and video traffi c where lost packets are simply ignored,
because there is no time to retransmit. If UDP is used and a reliable 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 c haracter consists of two bars and two
spaces, each of which is any of four widths. The standard symbology for reta il food packages in the United States.
V
Visible Laser Diode (VLD). A solid state device which produces visible laser light.