ISO/IEC 9995
ISO/IEC 9995 Information technology — Keyboard layouts for text and office systems is an ISO/IEC standard series defining layout principles for computer keyboards. It does not define specific layouts but provides the base for national and industry standards which define such layouts.
The project of this standard was adopted at ISO in Berlin in 1985 under the proposition of Dr Yves Neuville. The ISO/IEC 9995 standard series dates to 1994 and has undergone several updates over the years.
Parts
The ISO/IEC 9995 standard series currently consists of the following parts:- ISO/IEC 9995-1:2009 General principles governing keyboard layouts
- ISO/IEC 9995-2:2009 Alphanumeric section
- * ISO/IEC 9995-2:2009/Amd 1:2012
- ISO/IEC 9995-3:2010 Complementary layouts of the alphanumeric zone of the alphanumeric section
- ISO/IEC 9995-4:2009 Numeric section
- ISO/IEC 9995-5:2009 Editing and function section
ISO/IEC 9995-6:2006 Function section - ISO/IEC 9995-7:2009 Symbols used to represent functions
- * ISO/IEC 9995-7:2009/Amd 1:2012
- ISO/IEC 9995-8:2009 Allocation of letters to the keys of a numeric keypad
- ISO/IEC 9995-9:2016 Multilingual-usage, multiscript keyboard group layouts
- * ISO/IEC 9995-9:2016/Amd 1:2019
- ISO/IEC 9995-10:2013 Conventional symbols and methods to represent graphic characters not uniquely recognizable by their glyph on keyboards and in documentation
- ISO/IEC 9995-11:2015 Functionality of dead keys and repertoires of characters entered by dead keys
ISO/IEC 9995-1
ISO/IEC 9995-1 provides a fundamental description of keyboards suitable for text and office systems, and defines several terms which are used throughout the ISO/IEC 9995 standard series.Physical division and reference grid
The figure shows the division of a keyboard into sections, which are subdivided into zones.- alphanumeric section
- * alphanumeric zone
- * function zones
- numeric section
- * numeric zone
- * function zone
- editing and function section
- * cursor key zone
- * editing function zone
By means of the reference grid, each key can be identified by a unique combination of a letter and a sequence of two digits. E.g., the key visually marked as "1" on several layouts is identified as “Key E01”. The labeling rules do allow for function keys to be arranged in a position other than above the alphanumeric section, or to be arranged in more than one row :
- Columns containing editing or function keys are to be numbered from 60 on when placed beyond a right numeric section, or from 80 downwards when placed left of the alphanumeric section.
- Rows above of the alphanumeric section are to be labeled from K on, and rows below the space key are to be labeled from Z downwards.
The standard does not constrain the numbers of rows and columns in the alphanumeric section.
Levels and groups
The selection of level and group during the input of a character is specified in ISO/IEC 9995-2.Levels (“unshifted” “shifted”, “AltGr”)
The characters which can be input by the keys in the alphanumeric section usually are organized in levels. For two-cased scripts like Latin, the basic level contains lower-case letters, while the “Level 2” contains capital letters. For characters which are not letters, no rules are given regarding their distribution among the levels. While digits are commonly in Level 1, there are exceptions.The standard allows for a third level. Usually, characters in such a level are selected by the means of an AltGr key.
Groups
If the organization into three levels is not sufficient to accommodate all characters to be contained in a specific layout, then "groups" may be defined, which then constitute a higher hierarchical unit than levels. Thus, each such group is usually subdivided into up to three levels. Common examples are layouts allowing the input of characters of different scripts. On the Japanese keyboard layout, the kana constitutes the second group. The Canadian Québec layout and the German T2 layout allow the input of considerably more characters than their preceding editions, to overcome the historic limits of mechanical typewriters.The "Group selector" is defined in ISO/IEC 9995-2. As the US-International layout has four levels, the AltGr key or level 3 selector is repurposed as a group selector for the secondary group. Before ISO/IEC 9995-2, the new secondary group was called third level and fourth level. On layouts complying to ISO/IEC 9995-2’s initial design, the simultaneously pressed Shift and AltGr keys act as a group selector, since level 4 is prohibited as inaccessible, much like level 2 and level 3 are inaccessible depending on the disability, which is addressed by the sticky keys feature.
Depictions on the keytops
According to ISO/IEC 9995-1, the level is indicated by the row where the character is depicted on the keytop:- Level 2 above of Level 1
- Level 3 below Level 1.
- The first or “primary group” at the left keytop border
- The second or “secondary group” at the right keytop border
- Additional groups in between.
Thus, on the depicted key of the German T2 layout, in the primary group are the characters “#” in Level 1, “'” in Level 2, and “®” in Level 3. In the secondary group, there is the lowercase letter “ə” in Level 1 and its capital counterpart “Ə” in Level 2.
For layouts containing only one group, characters in Level 3 may be depicted in the lower right corner of a keytop, to allow larger depictions for ergonomic reasons. For instance, on the depicted key of the German T1 layout, the “\” is in Level 3, to be accessed by the AltGr key.
ISO/IEC 9995-2
ISO/IEC 9995-2 specifies requirements for the keys contained in the alphanumeric section.The alphanumeric zone has to contain 47 or more keys used to input characters, including the Space bar which has to be placed in the lowest row. Also, there must be:
- at least 12 keys in row E in positions E00 to E15, containing all keys to input the decimal digits,
- at least 12 keys in row D in positions D01 to D15,
- at least 11 keys in row C in positions C01 to C15,
- at least 10 keys in row B in positions B00 to B11.
Layouts which are designed for the Latin script must contain at least the 26 basic letters A…Z and a…z, the decimal digits 0…9, and the following characters contained in ISO 646: !
The keys shown grey in the figure, all being function keys, constitute the left and right function zones, while all other keys constitute the alphanumeric zone. The reference grid position of any function key may vary according to the specifications listed below. Especially, on a keyboard with considerably more than 47 keys in the alphanumeric zone, the right function keys will get higher column numbers.
The symbols shown for the function keys are specified in ISO/IEC 9995-7. Letterings which are commonly used instead of the symbols are shown in their English version in parentheses.
The [|harmonized 48 graphic key keyboard arrangement]
Keyboards which comply to this narrower specification contain all the keys shown in white in the figure above, the key at C12 shown in yellow, and one of the two keys at E13 and B00 shown in red. The standard does not require this; it only says that keyboards complying to this narrower specification can be called such.A key at E00 is not required, but when it is present on the keyboard, the positions E13 and B00 may have no key ; but most international layouts having a key at E00 also have at least one key on E13 or B00. Key at E00 may also be used to allocate a function key, in which case a key will generally be present at E13, or B00, or both.
In fact, several layouts, to allow a wider return key, have a key at D13 instead of C12. Thus, while they cannot be called “harmonized 48 graphic key keyboards” according to the standard, they still comply to the standard itself. ISO/IEC 9995-3:2010, in referring to the basic layout within its specific scope, does take a possible substitution of C12 by D13 into account.
Function keys
A tabulation key shall be present, occupying position D00.A key providing one of the functions Capitals lock, Level 2 lock, or Generalized lock shall be present, occupying the position C00.. The specific way the Caps Lock or Shift Lock works is not specified in the ISO/IEC 9995 series. Thus, solutions avoiding the status dependency as well as the problem of inadvertent hitting would not prevent compliance to the standard.
A Return key has to be present, right of the character input keys in row C. It is recommended that it expands to row D, as it e. g. does on the German layout.
A key providing one of the functions Backspace or Backward erase shall be present in row A or Row E, right of the character input keys.
If at least one Alternate key is present, it is to be positioned left of the space bar.
If at least one Control key is present, it has to be placed leftmost in row A, or row B.
If a Function key is present, it is to be positioned left the space bar and left of an “Alternate” key, if such one is present.
Level and group selection
To select the Level 2, two keys shall be present in row B. The left one shall occupy position B99, while the right one shall be located right of the character input keys of that row. The exact function of these keys is not specified in the standard. Thus, solutions where the shift key is pressed, then released before the character input key is pressed, are compliant with the standard.To select the Level 3, at least one Level 3 select key shall be present. On keyboards compliant to the “harmonized 48 graphic key keyboard arrangement”, such keys shall be placed in row A or row B. Like for the shift keys, the exact function of these keys is not specified in the standard.
For layouts containing more than one group, several mechanisms for group selection are specified. A dedicated Group selection key, if present, shall be positioned adjacent to a “Level 3 select” key. For layouts containing a “Group 2” as specified in ISO/IEC 9995-3, this key shall work as a “latch”. If no dedicated “Group selection” key is present, its function is obtained by pressing the “Level 2 select” and “Level 3 select” key simultaneously and releasing them before actuating the selected character input key.
Allocation guidelines for layouts containing the Latin alphabet
An informative annex “Allocation guidelines” provides a basic pattern for arrangements of Latin letters, which in fact specifies a foundation for the kinds of keyboard layouts known as QWERTY, QWERTZ, or AZERTY. As this annex is not normative, it does not prevent other arrangements like the Dvorak keyboard or the Turkish F-keyboard being compliant to the ISO/IEC 9995 standard series.The figure shows letters in black where a unique position is given, while the letters shown in red may alternatively occupy any of the positions where they are shown. Digits may be allocated on Level 0 or Level 1. An asterisk indicates “any other character”.
Numeric keypad emulation
The amendment 1 of ISO/IEC 9995-2:2009, which was published in 2012, specifies two ways of the emulation of a numeric keypad within the alphanumeric section of a keyboard. One way, with mappings to keys in the left half of the alphanumeric section, emulates a numeric keypad with the digits 1,2,3 in the upper row. The other way, with mappings to keys in the right half, emulates one with the digits 7,8,9 in the upper row. The affected keys of any emulation, if in effect, are to be pressed simultaneously with the Function key to provide the effect of the according key of a numeric keypad.ISO/IEC 9995-3
Common secondary group
ISO/IEC 9995-3:2010 defines a common secondary layout for the alphanumeric keyboard. These are engraved on the right part of the keytops; the standard defines their position independent of the characters of the primary layout. Thus, e. g. the Yen symbol “¥” occupies the shifted position on the 6th letter key of the second row, whether this is the Y key on a QWERTY keyboard or the Z key on a QWERTZ keyboard.Diacritical marks and peculiar characters
The diacritical marks contained in the common secondary group act as dead keys, i.e. they are to be entered before the base characters they apply to. This mechanism is also to be used for sequences of more than one diacritical marks, to write languages like Vietnamese and Navajo.Moreover, ISO/IEC 9995-3:2010 defines a list of “Peculiar Characters which can be entered as combinations using diacritical marks”.
This list specifies combinations of a diacritical mark and a second key. E.g., symbols like the not-equal sign “≠” can be entered this way. Especially, letters with a horizontal stroke are entered this way using the "horizontal stroke accent" located on the K key.
Outdated common secondary group
The third edition ISO/IEC 9995-3:2010 additionally defines an “outdated common secondary group” for compatibility purposes only. This resembles the “common secondary group” defined in the earlier edition of the standard, ISO/IEC 9995-3:2002. The CSA keyboard also named “Canadian Keyboard Standard for the English and French Languages” used mostly in the province of Quebec is based on this version.Complementary Latin group layout
For cases where no national keyboard layout is available, or to be used as an additional group on layouts designed for other scripts than Latin, the standard specifies a “Complementary Latin group layout”. It is based on the “harmonized 48 graphic key keyboard arrangement” as defined in ISO/IEC 9995-2. The assignment shown with red background shall occur once at one of the indicated positions.ISO/IEC 9995-4
ISO/IEC 9995-4 specifies the layout of the numeric section of a keyboard, if such one exists. It is subdivided into the function zone and the numeric zone. The leftmost key in the lowest row may span to the left, occupying the position shown with yellow background.The decimal digits 1…9 may be arranged in a “1-2-3 layout”, or in a “7-8-9 layout”.
On a keyboard used for telematic functions, the symbols and represent the initiator and the terminator. On a keyboard used for office purposes, the key denoted by shall show the decimal separator. On such keyboards, the key position marked by the asterisk may be an extension of the “0” key, or a “double zero” key. Accordingly, if the yellow key position is used, it may be also an extension of the “0” key, a “double zero” key, or a “triple zero” key.
The keys in the function zone may be associated to the arithmetic function they denote, or to the arithmetic characters, dependent of the software which is used. If an additional tabulator key or another special key is used, it shall be located at the position C54, thus occupying the lower half of the place shown for the “=” key.
Numeric sections on usual keyboards for personal computers do not comply to the standard, as they usually have a Num lock key in the upper left corner where the standard requires the “+” key, and therefore also show a different arrangement of the other arithmetic keys. By this, the standard in its present form can be considered outdated.
ISO/IEC 9995-5
ISO/IEC 9995-5 specifies the layout of the editing and function section of a keyboard. In fact, it specifies only two items:- The Escape key has to be at the position K00 according to the reference grid specified in ISO/IEC 9995-1, or to the left of it.
- The four cursor keys in the cursor key zone have to be arranged in a “cross layout” or an “inverted T layout”. The recommended placement is such that the “cursor down” key is placed on row A.
ISO/IEC 9995-7
ISO/IEC 9995-7 specifies several keyboard symbols to be used on function keys more commonly labelled with text such as the Escape, Alt or Insert keys. Some of these symbols have been encoded as Unicode code points; the figure shown above in the ISO/IEC 9995-2 section shows several examples. The rest have been proposed for encoding, but have been postponed pending evidence of use in running text other than by ISO and DIN. They are used extensively e. g. in the keyboard standard of the Province of Quebec, Canada.ISO/IEC 9995-8
file:Telephone-keypad.svg|thumb|upright 0.5 |ISO 9995-8 US keypad layout that may be used for text messaging.ISO/IEC 9995-8:2009 defines an assignment identical to E.161 of the 26 letters A–Z to the number keys of a numeric keypad. The space character is not assigned.