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Glossary
Issue 1 December 1997 GL-21
TL1
Transaction Language 1 — A Bellcore machine-to-machine communications language
that is a subset of ITU-TSS, formerly CCITT's, human-machine language.
TLB
Timing Looped Back. Used in synchronization messaging.
TOP
Task Oriented Practice
TR
Bellcore Technical Requirement
TSA
Time Slot Assignment
TSI
Time Slot Interchange
TSO
Technical Support Organization — Supports RTAC and the customers.
U
UAS
Unavailable Seconds. In performance monitoring, the count of seconds in which a signal
is declared failed or, in which, 10 consecutively severely errored seconds (SES) occurred,
until the time when 10 consecutive non-SES occur.
Unidirectional
A protection switching mode in which the system at each end of an optical span monitors
both service and protection lines and independently chooses the best signal (unless
overridden by an equipment failure or by an external request, such as a forced switch or
lockout). In a system that uses unidirectional line switching, both the
service
and
protection
lines may be
active
simultaneously, with one line carrying traffic in one direction
and the other line carrying traffic in the other direction. For a 1+1 protection scheme the
K1 and K2 bytes in the SONET line overhead are used to convey to the far end which line
the near end receiver has chosen, so that an "active" indication may be made at the far
end.
UOC
Universal Optical Connector — Receptacles on the faceplate of some OLIUs that accept
ST
, SC, or FC connectors.
UPD/INIT
A pushbutton on the user panel.
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