NonStop S-Series System Expansion and Reduction Guide

Glossary
G-Series Common Glossary
Glossary-28
effective group ID
effective group ID. An attribute of an Open System Services (OSS) process that is used to
determine permissions such as the file access allowed for the process. The effective
group ID of a process is a group ID that contributes to the group access privileges of
that process. The effective group ID of a process might be used to set the group ID of
files created by that process. The effective group ID can be changed while the process
runs.
effective user ID. An attribute of an Open System Services (OSS) process that is used to
determine such permissions as the file access allowed for the process. The effective
user ID of a process is the user ID that determines the owner access privileges of that
process. The effective user ID of a process might be used to set the user ID of files
created by that process. The effective user ID can be changed while the process runs.
EIA. Electronic Industries Association.
electric utility. The local utility service that, for a fee, supplies alternating-current (AC)
power to businesses and residences.
electromagnetic interference (EMI). Forms of conducted or radiated interference that
might appear in a facility as either normal or common-mode signals. The frequency of
the interference can range from the kilohertz to gigahertz range. However, the most
troublesome interference signals are usually found in the kilohertz to low megahertz
range. At present, the terms electromagnetic interference and radio frequency
interference (RFI) are usually used interchangeably.
electrostatically shielded transformer. A transformer that has a metallic shield placed
between the primary and secondary windings. This shield diverts high-frequency
signals to ground.
electrostatic discharge (ESD) protection kit. A kit containing an antistatic mat and a
wriststrap with a cable and grounding clip. A service provider or customer wears the
wriststrap while performing maintenance procedures inside an enclosure. The
wriststrap and cable contain grounding wires. When the grounding clip is attached to a
metal object, such as the enclosure, the person wearing the wriststrap is grounded.
Any static electricity incurred during the procedure is discharged safely to the
enclosure instead of to electrical components within the enclosure.
ELF. See extended link format (ELF).
emergency power off (EPO). Describes equipment used to automatically disconnect all
electrical power to connected equipment if an emergency occurs. A computer room’s
main EPO system shuts off all room equipment (except for lighting and fire-sensor
equipment) if a fire occurs. An equipment zone EPO shuts off power to all connected
computer equipment if a power anomaly occurs.
emergency power-off (EPO) connector. A two-pin connector on the service side of an
enclosure that allows an external signal to disable the batteries in the enclosure during
emergency conditions. A cable is attached from the connector to a relay band or push
button typically located near the door of a computer room. Pushing the EPO button