NonStop System Glossary

on the Y is 120 degrees. The center point of the Y is the common return point for the neutral
conductor.
wye-delta
The interconnections between a wye source and a delta load.
X
X fabric
The X side of the internal or external ServerNet fabrics. See also fabric, external ServerNet X or
Y fabric, and internal ServerNet X or Y fabric.
X.21
A digital signaling interface recommended by the International Telecommunications Union,
Telecommunication Standardization Sector (ITU-T) that includes specifications for data terminal
equipment/data communications equipment (DTE/DCE) physical interface elements, alignment of
call control characters and error checking, elements of the call control phase for circuit switched
services, data transfer at or below 9600 bits/second, and test loops.
XEP table
See external entry-point (XEP) table.
XIO
See extensible input/output (XIO).
XLLink
An Accelerator-related tool invoked by SYSGENR only for TNS/R systems. XLLink binds together
separately accelerated modules of TNS library code to make system libraries. XLLink preserves
and fixes up the existing Accelerator-generated MIPS RISC code, avoiding the additional time
needed for a complete acceleration from TNS instructions. XLLink is not supported for program
files, user libraries, or shared run-time libraries.
XO bond
The bond connection on an isolation transformer, installed between the transformer’s neutral XO
terminal and ground. This bond is required at North American and British sites to provide an
effective return path for any equipment conductor fault current back to the neutral of the isolation
transformer.
Y
Y fabric
The Y side of the internal or external ServerNet fabrics. See also fabric, external ServerNet X or
Y fabric, and internal ServerNet X or Y fabric.
$YMIOP
The name of the maintenance I/O process that is built during system generation and is available
at system startup.
X 205