E-Rate Terminology: Technology Glossary X

Resources > Technology Glossary

Search Our Site

Receive the
E-rate Weekly
Newsletter

Technology Glossary

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | +

Select a letter above to access the technology glossary in alphabetical order.
Select + for miscellaneous.

X.21 - ITU-T standard for serial communications over synchronous digital lines. The X.21 protocol is used primarily in Europe and Japan.

X.25 - a well-established data switching and transport method that relies on a significant
amount of processing to ensure reliable transport over metallic media.

XFR - TransFeR.

XTI - A common programming interface between the application and the transport layers of communications protocol.

Yellow Alarm - An alarm signal sent back toward the source of a failed signal due to the presence of an AIS (may be used by APS equipment to initiate switching).

Zener Diode - A type of semiconductor which acts as a normal rectifier until the voltage applied to it reaches a certain point. At that point (the zener voltage or avalanche voltage), the diode becomes conducting.