Created by: Terence Eden – Joe Loughry – Bruce 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.
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.
| 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 |
| 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 |
| 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 |
| 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 |
| 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.
| 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
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.