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Created by: Terence EdenJoe LoughryBruce Nordman
16th January 2014
Download the proposal in PDF.

Abstract

The international symbol IEC 60417-5009 meaning ‘power’ is not in Unicode.

Clearly it would be useful to anyone writing technical or user manuals. Furthermore, for electronically published documentation, it is crucial for this and a few other symbols to be defined because it makes them searchable in plain text. In this proposal we provide a TrueType font named ‘IECsymbol’ containing the glyphs as specified in three international standards together with all of the needed character properties for Unicode specification as well as evidence that the characters have been used in running text for thirty years.

Introduction

The , , , and symbols are defined in IEC 60417, which is also ISO 7000:2012.
IEEE 1621 defines and refines the definition of , notably by saying:

IEC 60417 defines for use with a power switch that does not do a total mains disconnect, and hence the device consumes standby power. is generally used and understood to mean “power,” as on power buttons, indicators, and elsewhere. , therefore, means “power” with a nonzero power level in the off state. Electronic devices shall use to be a synonym for “power” on power controls.

IEEE Standards Association. IEEE Standard for User Interface Elements in Power Control of Electronic Devices Employed in Office/Consumer Environments, 2004. IEEE Std 1621-2004. §4.3, emphasis in original.

IEEE 1621 standardises current practice for devices with regard to the symbol and introduces for sleep.
Bruce Nordman, Alan Meier, and Don Aumann. Toward a standard user interface for power controls. In Proceedings: 2002 Summer Study on Energy Efficiency in Buildings. LBNL-49665, 2002.

These characters, particularly , are needed for technical writing and are not in Unicode. The advantage of having them there would be that for the first time they would be searchable in plain text, something not possible with embedded graphics, which is the way the symbols have been displayed to date.

Suitability for Inclusion

These symbols are characters according to the definition in the Glossary, and do not appear in the Archive of Notices of Non-Approval. They are neither in the Pipeline Table nor in BETA. They are all widely used on equipment and in documentation (Figures 1–10). It would benefit technical writers and readers if they were available in Unicode because it would make user manuals and other technical documentation searchable in plain text.

We provide along with our proposal a TrueType font, with no restrictions on its use.

Evidence of Use in Running Text

Figures 1–10 show evidence of the use of each of these symbols in running text during the past thirty years.

Figure 1: Example of usage in running text from 2011, in the installation guide for a network analyser. From Agilent Technologies. Agilent E5071C ENA Series RF Network Analyzers Installation Guide, eighth edition, September 2011., Chapter 2, p. 24.
Figure 1: Example of usage in running text from 2011, in the installation guide for a network analyser. From Agilent Technologies. Agilent E5071C ENA Series RF Network Analyzers Installation Guide, eighth edition, September 2011., Chapter 2, p. 24.


Figure 2: Example of usage in running text from 2007, in the user’s guide for a computer. From Apple, Inc. Mac Pro User’s Guide, 2007., Chapter 1, p. 12.
Figure 2: Example of usage in running text from 2007, in the user’s guide for a computer. From Apple, Inc. Mac Pro User’s Guide, 2007., Chapter 1, p. 12.


Figure 3: Example of usage in running text from 2009, in the setup guide for a printer. From Hewlett–Packard Development Company, L.P. HP Photosmart D110 series, 2009., p. 2.
Figure 3: Example of usage in running text from 2009, in the setup guide for a printer. From Hewlett–Packard Development Company, L.P. HP Photosmart D110 series, 2009., p. 2.


Figure 4: Example of 1, S, and 0 usage in running text from 2004, in a standards document. From IEEE Standards Association. IEEE Standard for User Interface Elements in Power Control of Electronic Devices Employed in Office/Consumer Environments, 2004. IEEE Std 1621-2004., §4.5.2, p. 7.
Figure 4: Example of , , and usage in running text from 2004, in a standards document. From IEEE Standards Association. IEEE Standard for User Interface Elements in Power Control of Electronic Devices Employed in Office/Consumer Environments, 2004. IEEE Std 1621-2004., §4.5.2, p. 7.


Figure 5: Example of 0 and 1 usage in running text from 1984, in the user manual for a computer. From International Business Machines Corporation. IBM Personal Computer Hardware Reference Library: Guide to Operations, revised edition, 1984., p. 1-11.
Figure 5: Example of and usage in running text from 1984, in the user manual for a computer. From International Business Machines Corporation. IBM Personal Computer Hardware Reference Library: Guide to Operations, revised edition, 1984., p. 1-11.


Figure 6: Example of usage in running text from 2010, in the installation guide for a cable modem. From Motorola, Inc. Motorola SURFboard SB6121 DOCSIS 3.0 Cable Modem: Installation Guide, 2010., p. 7.
Figure 6: Example of usage in running text from 2010, in the installation guide for a cable modem. From Motorola, Inc. Motorola SURFboard SB6121 DOCSIS 3.0 Cable Modem: Installation Guide, 2010., p. 7.


Figure 7: Example of used in running text, in a monograph from 2002. From Bruce Nordman. Power switch labeling for medical and other devices. Technical report, Lawrence Berkeley National Laboratory, November 18, 2002., p. 4 (used by permission).
Figure 7: Example of and used in running text, in a monograph from 2002. From Bruce Nordman. Power switch labeling for medical and other devices. Technical report, Lawrence Berkeley National Laboratory, November 18, 2002., p. 4 (used by permission).


Figure 8: Example of 1, 0, T, and P usage in running text, in a monograph from 2002. From Bruce Nordman. Power switch labeling for medical and other devices. Technical report, Lawrence Berkeley National Laboratory, November 18, 2002., p. 2 (used by permission).
Figure 8: Example of , , , and usage in running text, in a monograph from 2002. From Bruce Nordman. Power switch labeling for medical and other devices. Technical report, Lawrence Berkeley National Laboratory, November 18, 2002., p. 2 (used by permission).


Figure 9: Example of S used in running text, in a monograph from 2002. From Bruce Nordman. Power switch labeling for medical and other devices. Technical report, Lawrence Berkeley National Laboratory, November 18, 2002., p. 2 (used by permission).
Figure 9: Example of used in running text, in a monograph from 2002. From Bruce Nordman. Power switch labeling for medical and other devices. Technical report, Lawrence Berkeley National Laboratory, November 18, 2002., p. 2 (used by permission).


Figure 10: Example of 0 and 1 used in running text from 2013, in the operator’s manual for a coffee maker. From Ugolini S.p.A. Delice 5L carnet d’instructions, 2013., p. 18.
Figure 10: Example of and used in running text from 2013, in the operator’s manual for a coffee maker. From Ugolini S.p.A. Delice 5L carnet d’instructions, 2013., p. 18.

Character Properties

Suggested character properties for the proposed symbols are given in Tables 1–5. These are the same names as in IEEE 1621-2004. None of the proposed names appear already in the Character Name Index.

Table 1: Suggested character properties for .
Property Suggested Value
Code point to be determined
Name POWER
General Category So
Canonical Combining Class 0
Bidirectional Class ON
Decomposition Type/Decomposition Mapping
Numeric Type
Numeric Value
Bidi Mirrored N
Unicode 1 Name
ISO Comment
Simple Uppercase Mapping
Simple Lowercase Mapping
Simple Titlecase Mapping
Table 2: Suggested character properties for .
Property Suggested Value
Code point to be determined
Name OFF
General Category So
Canonical Combining Class 0
Bidirectional Class ON
Decomposition Type/Decomposition Mapping
Numeric Type
Numeric Value
Bidi Mirrored N
Unicode 1 Name
ISO Comment
Simple Uppercase Mapping
Simple Lowercase Mapping
Simple Titlecase Mapping
Table 3: Suggested character properties for .
Property Suggested Value
Code point to be determined
Name SLEEP
General Category So
Canonical Combining Class 0
Bidirectional Class ON
Decomposition Type/Decomposition Mapping
Numeric Type
Numeric Value
Bidi Mirrored N
Unicode 1 Name
ISO Comment
Simple Uppercase Mapping
Simple Lowercase Mapping
Simple Titlecase Mapping
Table 4: Suggested character properties for .
Property Suggested Value
Code point to be determined
Name ON
General Category So
Canonical Combining Class 0
Bidirectional Class ON
Decomposition Type/Decomposition Mapping
Numeric Type
Numeric Value
Bidi Mirrored N
Unicode 1 Name
ISO Comment
Simple Uppercase Mapping
Simple Lowercase Mapping
Simple Titlecase Mapping
Table 5: Suggested character properties for .
Property Suggested Value
Code point to be determined
Name ON/OFF
General Category So
Canonical Combining Class 0
Bidirectional Class ON
Decomposition Type/Decomposition Mapping
Numeric Type
Numeric Value
Bidi Mirrored N
Unicode 1 Name
ISO Comment
Simple Uppercase Mapping
Simple Lowercase Mapping
Simple Titlecase Mapping

4.1 Collation Order

There is no required collation order, although there is an implied state transition ordering:

Power states shall be understood to have physical relationships to each other. Specifically, on is taken to be above sleep, and sleep above off.
IEEE Standards Association. IEEE Standard for User Interface Elements in Power Control of Electronic Devices Employed in Office/Consumer Environments, 2004. IEEE Std 1621-2004., §4.4, emphasis in original.

We suggest , , , , . They exhibit no shaping behaviour and have no particular required sorting order (except see the quoted paragraph above). The characters are uncased. There is no special line-breaking behaviour required.
These characters are not meant for use in identifiers, although they have been used for such (This web site has a collection of more than thirty examples of IEC 60417-5009 used in logo design).

They are stand-alone symbols. They are not white-space characters and have no numeric values. They are neither combining characters nor punctuation.

5 The IECsymbol TrueType Font

The five symbols included in the IECsymbol TrueType font are shown in Table 6.

Only these symbols exist in the font; if an undefined character, for example ‘A’ is called for in the font, the result is implementation-defined.

Placement of symbols in the IECsymbol TrueType font was chosen thoughtfully so as to be mnemonic: ‘P’ for power, ‘S’ for sleep, ‘T’ for toggling power on or off, and ‘1’ and ‘0’ for power-on and power-off, respectively; these mnemonics ‘fail gracefully’ in text should the IECsymbol font happen to be unavailable.

Table 6: All of the available glyphs in the IEC power TrueType font.
Symbol Applicable Standard(s) Character to Type Mnemonic Meaning)
IEC 60417-5009 P power Power
IEC 60417-5010 T toggle Power on/off
IEC 60417-5008 0 binary zero Power off
IEC 60417-5007 1 binary one Power on
IEEE 1621 S sleep Sleep

In text with normal spacing, the characters look like this .
The spacing around in the font appears wider because the glyphs are fixed-width.

6 Anticipated Objections

It might be argued that the meaning of is disputed between IEC 60417 and IEEE 1621, i.e., that IEC 60417 (as well as ISO 7000:2012) defined to mean ‘stand-by’ and IEEE 1621 changed it to mean ‘power’.

We counter that the issue is irrelevant to the Unicode Consortium for two reasons: firstly, because the symbol itself is needed by writers, regardless of the fact that ‘stand-by’ has no consistent definition (the term is routinely used to mean off, sleep, on, and other meanings that do not map to a consistent power state at all.); and secondly, because IEEE 1621 specifically codifies existing practice; the number of devices using to mean ‘power’ dwarfs the number of devices that use it to mean ‘stand-by’.
Furthermore:

No safety issue is introduced by the use of the symbol on a switch that causes the device to go to a hard-off state.

IEEE Standards Association. IEEE Standard for User Interface Elements in Power Control of Electronic Devices Employed in Office/Consumer Environments, 2004. IEEE Std 1621-2004., §4.3, emphasis in original.

There are, of course, many characters in Unicode already resembling circles (), or lines (), or the crescent moon (). None of the existing characters, however, has anything semantically to do with the concepts of ‘power’, ‘switch’, ‘toggle’, or ‘interrupter’. There are several occurrences of the crescent moon, but none showing the phase; IEEE 1621 intended the symbol to be different from other Unicode instances of a crescent moon. There are eleven occurrences of the word ‘power’ in Version 6.3.0 of the Unicode standard but none has anything to do with device control.

7 Drawing the Symbols

The proposed characters are not part of any script and the precise form of their drawing is not critical. As IEEE 1621-2004 says:

In accordance with IEC 80416-3, symbols can be filled, be rotated, have their lines thickened, or be used on digital displays, as long as an ordinary user can recognize the symbol correctly.

IEEE Standards Association. IEEE Standard for User Interface Elements in Power Control of Electronic Devices Employed in Office/Consumer Environments, 2004. IEEE Std 1621-2004. §4.3.

7.1 Severability

Of all the characters in Table 6, the most needed is .

We included the others in this proposal because they form a logical group. If, however, there is any objection to inclusion of , , , or , the one we really need is .

8 Sponsors

See PDF for details.

9 Summary and Conclusion

The , , , , and symbols are needed by technical writers to produce manuals in which these important symbols are searchable in plain text. Be-cause they were invented by the standards body to be distinctive, new, and unambiguous, there is no confusion with existing scripts. They have been in use in running text for at least thirty years. The suggested character properties are simple.

We provide along with this proposal a TrueType font called IECsymbol containing the new symbols; the TrueType font is made available with no restrictions.

Download the proposal in PDF.

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