IEEE P1621

December 15, 2002

Draft Standard for User Interface Elements in Power Control of
Electronic Devices Employed in Office/Consumer Environments

Sponsored by the

Microprocessor Standards Committee

of the

IEEE Computer Society

Copyright © 2002 by the Institute of Electrical and Electronics
Engineers, Inc.

Three Park Avenue

New York, New York 10016-5997, USA

All rights reserved.

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# Introduction

(This introduction is not part of IEEE P1621, Draft Standard for User
Interface Elements in Power Control of Electronic Devices Employed in
Office/Consumer Environments.)

The electronics industry has been proactive in including product
features that reduce power levels when possible to save energy, and
extend battery life. Much of this has been accomplished through industry
work with the U.S. EPA [Energy Star]{.smallcaps} program, and globally,
billions of dollars of electricity are saved each year through the use
of power management[^1]. Despite this success, many devices that are
capable of power management are not saving energy because the power
management features are disabled, incorrectly configured, or thwarted by
a hardware or software conflicts[^2]. For PCs, the great majority are
not power-managing. For monitors, printers, and copiers, the rates are
above 50%, but significant improvement is still possible. Thus, there is
the potential for considerable additional savings through higher
enabling rates in power management. In addition, there are a variety of
reasons to expect that the opportunity for energy savings from power
management will only increase in coming years, such as more devices and
device types that can power manage, greater number of hours these
devices are wanted to be available, and greater difference between on
and sleep states.

The goal of this standard is to capture energy savings by increasing the
rate at which power management features are enabled and operate
successfully. This standard should lead to other benefits such as
improved ease of use and reduced burden of customer support on
manufacturers.

At present, power management controls in office equipment and other
electronic devices show little consistency in the terms, symbols, and
indicators used and in their overall structure. This is particularly
true across device types (e.g. between a PC and a copier), but often
holds even within the same type of device. For example, the standby mode
on some copiers refers to the state when they are fully on and
immediately ready to act, but the standby mode on some computers and
monitors refers to a low-power mode in which they have reduced
capability and take time to recover. "Standby power" also is used for a
device's minimum power state, which is often when it is off. The
combination of controls and indications of power status is the user
interface.

The confusion and ambiguity of so many power controls precludes many
people from being able to understand power controls and power status.
The problematic interfaces further deter these people and others from
attempting to change power management settings or successfully doing so.

This standard is intended to accomplish a broad similarity of experience
of power controls of any electronic device that is used in a normal work
or home environment. It is intended to do this through voluntary means.
It is not intended to stifle innovation in user interfaces, nor preclude
deviations from the standard where clearly warranted.

At the time this standard was completed, the working group had the
following membership:

Bruce Nordman, *Chair*

The following members of the balloting committee voted on this standard.
Balloters may have voted for approval, disapproval, or abstention. (To
be provided by IEEE editor at time of publication.)

Contents

Introduction [ii](#introduction)

1\. Overview [5](#overview)

1.1 Scope [5](#scope)

1.2 Purpose [5](#purpose)

2\. References [5](#references)

3\. Definitions, terminology, and acronyms
[6](#definitions-terminology-and-acronyms)

3.1 General Definitions [6](#general-definitions)

3.2 Power State Definitions [7](#power-state-definitions)

4\. The Standard [7](#the-standard)

4.0 General Principles [7](#general-principles)

4.1 Power States [7](#power-states)

4.2 Power Symbols [8](#power-symbols)

4.3 Power Metaphors, Affordances, and Terminology
[9](#power-metaphors-affordances-and-terminology)

4.4 Power Indicators [10](#power-indicators)

4.5 Power Switch Labeling and Behavior
[11](#power-switch-labeling-and-behavior)

4.6 Wake Events [12](#wake-events)

4.7 Tactile Interfaces [12](#tactile-interfaces)

Draft Standard for User Interface Elements in Power Control of
Electronic Devices Employed in Office/Consumer Environments

# 1. Overview

## 1.1 Scope

This standard covers the user interface for the power status control of
electronic devices that ordinary people commonly interact with in their
work and home lives, including, but not limited to, office equipment and
consumer electronics.  Key elements are terms, symbols, and indicators. 

This standard does [not]{.underline}: specify maximum power levels;
address safety issues; or cover internal mechanisms or interfaces for
industrial devices.

## 1.2 Purpose

To accomplish a similarity of experience of power controls across all
electronic devices so that users will find them easier to use and be
more likely to utilize power management features that save energy.

# 2. References

This standard shall be used in conjunction with the following
publications. When the following standards are superseded by an approved
revision, the revision shall apply. See Annex A for informative
references. Uniform Resource Locators (URLs) provided in this standard
are current as of the date submitted for publication.

CIE Technical Report CIE 107-1994, Review of the official
recommendations of the CIE for the colours of signal lights,
International Commission on Illumination.

IEC 447:1993, Man-machine interface (MMI) --- Actuating principles.

IEC 60073:2002, Basic and safety principles for man-machine interface,
marking and identification---Coding principles for indication devices
and actuators.

IEC 60417-1:1998, Graphical symbols for use on equipment---Part 1:
Overview and application.

IEC 60417-2:1998, Graphical symbols for use on equipment---Part 2:
Symbol originals.

IEC 59/267/CD:62301:2002, Measurement of standby power. Draft.

IEC 80416-1:2001, Basic principals for graphical symbols for use on
equipment---Part 1: Creation of symbol originals.

IEC 80416-3:2002. Basic principals for graphical symbols for use on
equipment---Part 3: Guidelines for the application of graphical symbols.

ISO 7000:1989, Graphical symbols for use on equipment: Index and
synopsis.

ISO 9186:2001, Graphical symbols---Test methods for judged
comprehensibility and for comprehension.

ISO 9241-10:2001, Ergonomic requirements for office work with visual
display terminals (VDTs)---Part 10: Dialogue principles.

ISO 9241-1:1996, Ergonomic requirements for office work with visual
display terminals (VDTs)---Part 1: General introduction.

ISO/IEC 13251:2000, Collective Standard---Graphical symbols for office
equipment.

VITA 40-2002, Service Indicators.

# 3. Definitions, terminology, and acronyms

In this standard, to increase clarity, power states are *italicized*.

## 3.1 General Definitions

**3.1.1 device:** An electronic machine, usually a commercial product,
that is commonly used and interacted with by ordinary people in their
work or home life. This includes devices traditionally electronic, such
as office equipment and consumer electronics, as well as appliances,
telecommunications devices, space conditioning equipment, and any other
device that has non-trivial power controls. In this context, devices are
usually separately powered from the mains, separately controlled by the
user for their power status, and have a separate power indicator.

**3.1.2 manual power control:** An action taken by a user, or external
device (including network activity), to change the power state of the
device.

**3.1.3 power control:** The combination of manual power control and
automatic power management.

**3.1.4 power control panel:** A set of software controls for viewing
and/or changing parameters relevant to the power controls such as delay
timers, switch behavior, summaries of usage patterns, and device
behavior after unexpected power loss.

**3.1.5 power indicator:** A color, word, or other display that
communicates the power state of a device to a user. Common examples are
simple lights (e.g. a light emitting diode), text display (e.g. with a
liquid crystal display), or an element of a larger visual display. Power
indicators may also have audio or tactile indications.

**3.1.6 power management (automatic):** The active modulation of the
energy consumption of a device for purposes other than the intended
function of a product. Examples of other purposes are mains electricity
conservation, battery life extension, overheating avoidance, and noise
reduction from less fan noise.

**3.1.7 power state:** A condition or mode of a device that broadly
characterizes its capabilities, power consumption, power indicator
coding, and responsiveness to input. Basic power states are *on*,
*sleep*, and *off*. Devices may have multiple instances of one or more
of the basic states (e.g. *light sleep*, *deep sleep*), and need not
have any *sleep* states. All devices have at least one *on* state, and
at least one *off* state (*unplugged*). The term "power mode" may be
substituted and has identical meaning.

**3.1.8 power switch:** A user mechanism for causing a power state
transition. May also be called a "power button".

**3.1.9 tactile nib:** A small raised surface, usually on a key, that
does not interfere with normal usage but allows identification of the
key through tactile means only. May be also found on buttons or
switches. Common examples are "F", "J", and "5" keys.

**3.1.10 wake event:** A manual or automatic action that causes a system
to initiate a transition from a *sleep* power state to an *on* power
state.

## 3.2 Power State Definitions

**3.2.1 hard-off:** An *off* power state in which the device uses no
power from the mains or a normal operating battery.

**3.2.2 on:** A power state in which the device has greater (or similar)
power consumption, capability, and responsiveness than it does in the
*sleep* or *off* state.

**3.2.3 off:** A power state in which the device has less (or similar)
power consumption, capability, and responsiveness than it does in the
*sleep* or *on* state.

**3.2.4 sleep:** A power state in which the device has greater (or
similar) power consumption, capability, and responsiveness than it does
in the *off* state, and has less (or similar) power consumption,
capability, and responsiveness than it does in the *on* state.

**3.2.5 soft-off:** An *off* power state in which the device may use
some power from the mains or a normal operating battery. When it is
unknown whether the *off* power is zero, the *off* state shall be
considered to be *soft-off*.

**3.2.6 unplugged:** A form of the *off* power state in which all normal
operating power supplies have been disconnected. For devices that can
operate from battery power, this requires that the battery be removed or
otherwise disconnected from the ability to supply the system. A device
that is unplugged cannot be turned on until at least one source of the
power supplies is connected. Incidental battery power such as that which
supplies clock circuits but is not capable of powering the device in an
*on* state does not qualify as normal operating power. A battery which
provides only short-term operating power (e.g. for less than 1 minute)
also does not qualify.

# 4. The Standard

## 4.0 General Principles

This standard shall not be used to impede innovation in power controls,
nor shall it be used to prohibit deviations from the standard in cases
where the difference is clearly merited. The standard shall be
interpreted in ways that maximize consistency across devices and
simplicity and clarity for users.

## 4.1 Power States

Power states for this standard are *user* power states, and are not
required to correspond directly to internal power states. Devices shall
be limited to the three basic power states --- *on*, *sleep*, and *off*.
Any additional power states shall be variants of one of the basic states
rather than a fourth state.

This standard does not address absolute power levels, nor does it make
specifications about peak power consumption so that no restriction is
placed on short-term fluctuations in power levels.

Power levels for purposes of this standard are only relevant as they
affect long-term energy consumption. Thus, power should be measured over
an extended time period; IEC 62301 provides procedures for measuring
average power over such periods.

The only power consumption requirements of this standard for power
states are that:

Power~ON~ ≥ Power~SLEEP~ and Power~SLEEP~ ≥ Power~OFF~.

Common forms of *sleep* are *light sleep* and *deep sleep*. As with
basic power states, Power~LIGHT\ SLEEP~ ≥ Power~DEEP\ SLEEP~.

Common forms of *off* are *soft-off* and *hard-off*. *Soft-off* implies
that some power [may]{.underline} be consumed by the device even though
the power state is *off*. *Hard-off* [requires]{.underline} that no
power is consumed, either from mains power or a normal operating
battery.

### 4.1.1 User Experience of Power States

The *off* power state does not require information about the device
functional state to be lost. For example, a television may remember the
channel and volume settings when *off*, and a computer may remember its
functional state in *off* through the use of a "hibernate" feature,
saving the system state to non-volatile memory (e.g. a hard disk).

When feasible, devices shall have [consistent behavior]{.underline},
[responsiveness to input]{.underline}, and [capability to
act]{.underline} in all substates within a basic state. For example,
wake events shall be consistent across all sleep states when feasible.

Users shall not be [required]{.underline} to understand the differences
among substates to properly use a product, but devices are not
prohibited from communicating which substate the device is in.

When feasible, user interfaces shall not differ between *soft-off* and
*hard-off* except when the *hard-off* symbols need to be used. Users
should generally experience only *off*.

### 4.1.2 Relation between Power States and Operating System State

The state of a device operating system and the power state of the device
shall be differentiated, but may have common controls. For example, a
command to power on a device may also start the operating system, and a
command to power down may also shut down the operating system. However,
a device can be in a special mode and be *on* but without the primary
operating system operative, and a device can be *off* but have the
operating system state saved for immediate use after power on (this is
commonly called "hibernate").

A command to "restart" a device operating system is generally not a
power state transition, since the device usually begins and ends in the
*on* state. However, it is appropriate to present a restart operation as
a pair of power state transitions (power down immediately followed by
power up).

## 4.2 Power Symbols

Power symbols shall be those used in IEC 60417 as well as the sleep
symbol. The are listed in Table 1. IEC 60417 defines
![](media/image1.png){width="0.12361111111111112in"
height="0.14166666666666666in"} as for use with a power switch that does
not do a total mains disconnect, and hence the device consumes "standby"
power. ![](media/image1.png){width="0.12361111111111112in"
height="0.14166666666666666in"} is generally used and understood to mean
"power", as on power buttons, indicators, and elsewhere.
![](media/image1.png){width="0.12361111111111112in"
height="0.14166666666666666in"} therefore means "power" with a non-zero
power level in the *off* state. Electronic devices shall use
![](media/image1.png){width="0.12361111111111112in"
height="0.14166666666666666in"} to be a synonym for "power" on power
controls. Even if used on a power button that does go to a *hard-off*
state, that should not introduce any safety issue.

Table 1. Power Symbols

+-------+-------+------------------------------------------------------+
| **Sym | **N   | ### U                                                |
| bol** | ame** | sages in addition to use within power control panels |
+-------+-------+------------------------------------------------------+
| ![    | On    | On a switch, best used in conjunction with the Off   |
| ](med |       | symbol, as on a rocker switch.                       |
| ia/im |       |                                                      |
| age2. |       |                                                      |
| png){ |       |                                                      |
| width |       |                                                      |
| ="8.3 |       |                                                      |
| 33333 |       |                                                      |
| 33333 |       |                                                      |
| 3333e |       |                                                      |
| -3in" |       |                                                      |
| he    |       |                                                      |
| ight= |       |                                                      |
| "8.68 |       |                                                      |
| 05555 |       |                                                      |
| 55555 |       |                                                      |
| 555e- |       |                                                      |
| 2in"} |       |                                                      |
+-------+-------+------------------------------------------------------+
| !     | Off   | On a switch, best used in conjunction with the On    |
| [](me |       | symbol, as on a rocker switch.                       |
| dia/i |       |                                                      |
| mage3 |       |                                                      |
| .png) |       |                                                      |
| {widt |       |                                                      |
| h="0. |       |                                                      |
| 12361 |       |                                                      |
| 11111 |       |                                                      |
| 11111 |       |                                                      |
| 12in" |       |                                                      |
| h     |       |                                                      |
| eight |       |                                                      |
| ="0.1 |       |                                                      |
| 23611 |       |                                                      |
| 11111 |       |                                                      |
| 11111 |       |                                                      |
| 2in"} |       |                                                      |
+-------+-------+------------------------------------------------------+
| !     | O     | For use on a power switch that always switches to    |
| [](me | n/Off | *hard-off* in the *off* state. For use with a power  |
| dia/i |       | indicator if the off indication is always *hard-off* |
| mage4 |       | and the distinction from *soft-off* is important.    |
| .png) |       |                                                      |
| {widt |       |                                                      |
| h="0. |       |                                                      |
| 12361 |       |                                                      |
| 11111 |       |                                                      |
| 11111 |       |                                                      |
| 12in" |       |                                                      |
| h     |       |                                                      |
| eight |       |                                                      |
| ="0.1 |       |                                                      |
| 23611 |       |                                                      |
| 11111 |       |                                                      |
| 11111 |       |                                                      |
| 2in"} |       |                                                      |
+-------+-------+------------------------------------------------------+
| !     | Power | For use on a power switch or button if the *off*     |
| [](me |       | state is *soft-off*, is variable, is not known, or   |
| dia/i |       | the distinction from *hard-off* is not important.    |
| mage1 |       | Also for use with a power indicator, or as the icon  |
| .png) |       | for the power control panel.                         |
| {widt |       |                                                      |
| h="0. |       |                                                      |
| 12361 |       |                                                      |
| 11111 |       |                                                      |
| 11111 |       |                                                      |
| 12in" |       |                                                      |
| h     |       |                                                      |
| eight |       |                                                      |
| ="0.1 |       |                                                      |
| 41666 |       |                                                      |
| 66666 |       |                                                      |
| 66666 |       |                                                      |
| 6in"} |       |                                                      |
+-------+-------+------------------------------------------------------+
| !     | Sleep | For use on a sleep button, or with a sleep           |
| [](me |       | indicator.                                           |
| dia/i |       |                                                      |
| mage5 |       |                                                      |
| .png) |       |                                                      |
| {widt |       |                                                      |
| h="0. |       |                                                      |
| 19027 |       |                                                      |
| 77777 |       |                                                      |
| 77777 |       |                                                      |
| 77in" |       |                                                      |
| heigh |       |                                                      |
| t="0. |       |                                                      |
| 16736 |       |                                                      |
| 11111 |       |                                                      |
| 11111 |       |                                                      |
| 1in"} |       |                                                      |
+-------+-------+------------------------------------------------------+

In accordance with IEC 80416-3, symbols can be filled, rotated, have
their lines thickened, or used on digital displays, so long as the
meaning remains clear.

## 4.3 Power Metaphors, Affordances, and Terminology

Metaphors and affordances can be used in the construction of
terminology, documentation, and product design. For power controls, they
should be used as described below, but used precisely and sparingly.

Power states shall be understood to have physical relationships to each
other. Specifically, *on* is taken to be above *sleep,* and *sleep*
above *off*. Consequently, "power up" refers to a transition from *off*
to *on*, *off* to *sleep*, or *sleep* to *on*. "Power down" refers to a
transition from *on* to *off*, *on* to *sleep*, or *sleep* to *off*.
"Power on" refers to transition to an *on* state. "Power off" refers to
a transition to an *off* state.

For low-power modes, the "sleep" metaphor shall be used, for the name of
the power state, for transitions ("going to sleep", "waking up", and a
"wake event"), and for the sleep
symbol---![](media/image5.png){width="0.15in"
height="0.13333333333333333in"}.

User terminology used for controls for power states shall be organized
around the term "power". Common examples include a "power switch",
"power button", "power indicator", "power control panel", and "power
management". User terminology is often used on the outside of devices;
in documentation, and on displays.

For power indicators, the colors and color names "yellow", "amber", and
"orange" shall be considered to be equivalent, though orange is the
least preferred. This standard uses the name "yellow" to be consistent
with IEC 60073. The specific colors to use are specified in Section 4.4.
Care should be taken when translating the color names to other languages
that the term used for yellow is clearly not that used for any form of
"red".

Common terms used to refer to *on* states are *on*, *full-on*, *ready*
and *active*, but no difference in meaning is implied by this standard
to these different terms.

Standard translations of key terms shall be used in documentation, and
on products (when present). Key terms include: power, *sleep*, *on*, and
*off*.

## 4.4 Power Indicators

### 4.4.1 General Principles

Power indicators shall communicate stable device power states or
transitions between power states. Power indicators may also communicate
non-power-state information provided that ambiguity is not introduced.

### 4.4.2 Static Power States

For power indicators, color coding for power states shall be
[green]{.underline} for *on*, [yellow]{.underline} for *sleep*, and
[off]{.underline} for *off*. Black or gray may be substituted for off
(as on a graphic display or with a mechanical indicator). These color
assignments are consistent with IEC 60073.

For *sleep* indicators, color coding for power states shall be
[off]{.underline} for *on*, [yellow]{.underline} for *sleep*, and
[off]{.underline} for *off*.

Power indicator colors shall be used in accordance with CIE 1994, which
specifies color limits for traffic signal lights. For fully saturated
colors, green shall be between 498 *nm* and 508 *nm*; yellow between 585
*nm* and 593 *nm*; and red between 615 *nm* and 705 *nm*.

For text or graphic displays, *on* can be specified by the lack of
power-state information (and presence of other information), the term
"on" (or a clear synonym), or the on
symbol---![](media/image2.png){width="8.333333333333333e-3in"
height="8.680555555555555e-2in"}; *sleep* states can be communicated by
the term "sleep" or the sleep
symbol---![](media/image5.png){width="0.15in"
height="0.13333333333333333in"}; the *off* state can be communicated by
the display being off, use of the term "off", or the off
symbol---![](media/image3.png){width="0.12361111111111112in"
height="0.12361111111111112in"}. Table 2 presents a summary of power
state indications.

Table 2. Summary of power state indications

  ----------- ---------------- ----------- ------------------------------------------------------ -----------------------------------------
  **State/\   **Indicators**               **Symbol**                                             Text / Displays
  Term**                                                                                          

              Power            **Sleep**                                                          

  On          green            off         ![](media/image2.png){width="8.333333333333333e-3in"   The lack of power-state information (and
                                           height="8.680555555555555e-2in"}                       presence of other information). "On" may
                                                                                                  be substituted by a clear synonym,

  Sleep       yellow           yellow      ![](media/image5.png){width="0.15in"                   The term "sleep".
                                           height="0.13333333333333333in"}                        

  Off         off              off         ![](media/image3.png){width="0.12361111111111112in"    The display being *off*, or use of the
                                           height="0.12361111111111112in"}                        term "off".
  ----------- ---------------- ----------- ------------------------------------------------------ -----------------------------------------

Power indicators may be on remote devices. For example, a computer may
display the power state of other devices it can connect to. This allows
indications of an *off* state other than an indicator light or entire
display being off.

Some mechanical switches can reliably show the power state so long as
the device is powered.

For devices for which a constantly illuminated power indicator would use
excessive energy or be particularly intrusive, a brief flash of the
power indicator in the appropriate color is allowed (e.g. one tenth of a
second on followed by 1.9 seconds off).

Non-power information can be combined with power indications in the
following ways. An error indication can be shown with a red color in the
place of a power indication; when this is done, no power state
information is communicated. When red is unavailable, alternating green
and yellow at the normal flashing rate can be used to indicate an error,
but shall not be used to indicate that a safety hazard is present.
Alternating red and green or red and yellow shall be used to
simultaneously indicate an error condition and power status. Other
non-power-state information, such as communication occurring, can be
indicated by the slow flashing rate. Per IEC 60073, normal flashing
rates are 1.4 Hz to 2.8 Hz, and slow flashing rates are between 0.4 Hz
to 0.8 Hz.

### 4.4.3 Power State Transitions

From the user perspective, some devices change from one power state to
another instantly. For devices with user-perceptible transition times
*between* states (e.g. more than one second), the power indicator shall
communicate the fact of the transition state and its direction. Even for
instant transitions, a "blink" of the indicator is recommended as it
helps the user to see that the transition has occurred.

Color power indicators shall flash or otherwise modulate during
transitions, green for a "power up" transition, and yellow for a "power
down" transition. Text or graphic indications shall flash or provide
some other indication that there is a transition state. Flashing shall
be consistent with IEC 60073 normal flashing rates (1.4 Hz to 2.8 Hz).

Devices with audio capability shall have optional audio indications of
power state transitions. The audio indications shall be of one of the
types shown in Table 3.

Table 3. Audio indications of power state transitions

  ---------- ---------------------------------------------------------------
  **Type**   **Details**

  Click      A power-up transition shall be indicated by a single click or
             beep. A power down transition shall be indicated by a double
             click or beep.

  Tone       Powering up shall be indicated by a rising tone or two tones
             with the second having a higher pitch than the first. Powering
             down shall be indicated by the reverse (a falling tone or two
             tones with the second having a lower pitch than the first).
             *Sleep* shall be accommodated in these indications by using a
             tone with a pitch intermediate between the two tones used for
             *on* and *off*.

  Other      Other sound indications (e.g. musical notes or speech) shall
             clearly indicate the direction or endpoint of the transition.
  ---------- ---------------------------------------------------------------

Devices with extended transitions and the capability to display a
progress indicator shall display one. A progress indicator shall show
(via graphics or text) the estimated elapsed portion of the total
transition time or the time remaining in the transition.

## 4.5 Power Switch Labeling and Behavior

When feasible, pressing a power button shall toggle the device between
the two most commonly used power states. When a device is asleep, and
can wake itself up, pressing a power button shall wake up the device.

Power switches shall be one of two types: *hard-off* and *soft-off*.
When safety is involved, the user interface shall be unambiguous as to
whether an *off* state is *soft-off* or *hard-off*. When safety is not
involved, preference shall be given to the
![](media/image1.png){width="0.12361111111111112in"
height="0.14166666666666666in"} symbol.

The present set of international standard symbols for power control
lacks a workable designation for *soft--off* ---equipment that are
functionally *off* but continue to draw some power (the
![](media/image3.png){width="0.12361111111111112in"
height="0.12361111111111112in"} symbol is reserved for zero power).
Thus, designs should be avoided that would require such a symbol.

It is recommended that rocker switches be used for power controls
[only]{.underline} when *off* is a zero power state. It is also
recommended that push-button switches be used for power controls when
*off* is non-zero power. These usages avoid the need for a symbol that
clearly means the *off* power state, but means *soft-off*.

When a device has two power controls, or otherwise has a *hard-off* and
*soft-off* mode (with the *hard-off* obtainable other then by unplugging
from the mains or normal battery), both will have the power indicator
off. Only inspection or manipulation of the power switches will clarify
which mode it is in. When two power controls are present, the secondary
control should be labeled with
![](media/image1.png){width="0.12361111111111112in"
height="0.14166666666666666in"}.

For devices which need an emergency override, it shall be accomplished
by holding down a power button for at least four seconds. An emergency
override will usually force the device into an *off* state and is
necessary when ordinary means to do this are not possible.

In product design, consideration shall be given to the specifications of
IEC 60073 for actuators for *on* and *off*. However, this standard makes
no requirements for actuator colors. Among the specifications of IEC
60073arethat for a control that goes to *off*, [red]{.underline} may be
used and [green]{.underline} shall not be used; for controls to go to
*on*, [green]{.underline} maybe used and [red]{.underline} shall not be
used; and for controls that switch among power states, neutral color
such as [white]{.underline}, [grey]{.underline}, and [black]{.underline}
are preferred, [yellow]{.underline} and [green]{.underline} are not to
be used, and [red]{.underline} is to be used only in special
circumstances.

## 4.6 Wake Events

Devices with *sleep* states shall have one more wake events. When
feasible, wake events shall be consistent across all *sleep* states.
When feasible, pressing a power button shall cause a wake event.

For general purpose controls such as keyboards, and where the meaning of
a key press depends on mode information not apparent in the *sleep*
state, the wake event itself shall be discarded from the normal input
stream.

## 4.7 Tactile Interfaces

When a tactile marking is used on a power control, it shall be a single
nib or set of three nibs in a horizontal line on the power button or on
the "on" side of a power switch.

Tactile indications of states and transitions shall be broadly
consistent with those of the other modalities of this standard.

[^1]: Kawamoto, Kaoru and Jonathan G. Koomey, Bruce Nordman, Richard E.
    Brown, Mary Ann Piette, Michael Ting, and Alan K. Meier. 2002.
    Electricity used by office equipment and network equipment in the
    US. *Energy---the International Journal.* vol. 27, no. 3, pp.
    255-269. March, 2002.

[^2]: Nordman, Bruce, Alan Meier, and Mary Ann Piette. 2000. "PC and
    Monitor Night Status: Power Management Enabling and Manual
    Turn-off." In Proceedings of the ACEEE 2000 Summer Study on Energy
    Efficiency in Buildings, 7:89-99. Washington, D.C.: American Council
    for an Energy-Efficient Economy. Also, Webber, Carrie A., Judy A.
    Roberson, Richard E. Brown, Christopher T. Payne, Bruce Nordman, and
    Jonathan G. Koomey. 2001. Field Surveys of Office Equipment
    Operating Patterns. LBNL-46930. Berkeley, Calif.: Lawrence Berkeley
    National Laboratory.