Wikipedia:Manual of Style/Accessibility/Data tables tutorial: Difference between revisions
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{{Wikipedia how-to|interprets=Wikipedia:Manual of Style/Accessibility|WP:DTT|MOS:DTT|WP:DTABTUT|MOS:DTABTUT|MOS:DATATABLES}}
{{Style|content}}
{{Wikipedia:WikiProject Accessibility/Navigation menu|articles}}
This tutorial is a guideline which, as part of Wikipedia's [[WP:MOS|Manual of Style]], is intended to assist those creating data tables (or more often [[Wikipedia:Manual of Style/Lists|lists]]) in ensuring the content is [[Web accessibility|accessible to all]]. For more info on how to create and edit tables, see [[Help:Table]].
Guidelines on this page are ordered primarily by priority, then difficulty. The priority levels are determined by the Accessibility Success Criteria rankings A, AA, and AAA (in descending order of importance as accessibility considerations) of the [[World Wide Web Consortium]] (W3C) [[WCAG 2.0|Web Content Accessibility Guidelines (WCAG) 2.0]].<ref group="WCAG" name="WCAG2.0">{{cite web |title=Web Content Accessibility Guidelines 2.0 |date=5 May 1999 |work=W3.org |publisher=World Wide Web Consortium (W3C)|___location=Cambridge, Massachusetts |author=Web Accessibility Initiative |editor1-first=Wendy|editor1-last=Chisholm |editor2-first=John|editor2-last=Slatin |editor3-first=Jason |editor3-last=White |url= http://www.w3.org/TR/WAI-WEBCONTENT/ |accessdate=11 December 2008}}
The present system replaces the 1999 [http://www.w3.org/TR/WCAG10/ WCAG 1.0] system of Conformance Levels (also A, AA, and AAA) with a [http://www.w3.org/TR/WAI-WEBCONTENT/full-checklist.html checklist] of Priority 1, 2, and 3 recommendations; while those roughly correspond to the current A, AA, and AAA success levels, 2.0 has added many criteria that were not present in 1.0. See [http://www.w3.org/WAI/WCAG20/from10/diff.php "How WCAG 2.0 Differs from WCAG 1.0"]</ref> The {{em|difficulty}} indicates if it seems easy or not for Wikipedia users to comply to the guidelines.
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* Difficulty: easy (the syntax is fairly simple and editors get used to it; the layout might change users' habits)
===Table style===
<div style="display: inline-table;">
'''Wikitext:'''
<syntaxhighlight lang="wikitext">
{| class="wikitable"
Line 30 ⟶ 33:
|}
</syntaxhighlight>
</div>
<div style="display: inline-table;">
'''Produces:'''
{| class="wikitable"
|+ caption text
Line 44 ⟶ 50:
| data 3 || data 4
|}
</div>
A caption is a table's title, describing its nature.<ref name="H39" group="WCAG">[http://www.w3.org/TR/2008/NOTE-WCAG20-TECHS-20081211/H39 "H39: Using caption elements to associate data table captions with data tables"], accessibility level: A.</ref> ====Row and column headers (<code> ! </code>)====
Like the caption, these help present the information in a logical structure to visitors.<ref group="WCAG">[http://www.w3.org/TR/2008/NOTE-WCAG20-TECHS-20081211/H51 "H51: Using table markup to present tabular information"]</ref> The headers help screen readers render header information about data cells. For example, header information is spoken prior to the cell data, or header information is provided on request.<ref>[http://www.w3.org/TR/REC-html40/struct/tables.html#edef-TH Table cells: The TH and TD elements], W3C</ref>
====Scope of headers (<code>scope="col"</code> and <code>scope="row"</code>)====
This clearly identifies headers as either column headers or row headers respectively.<ref group="note">See [http://www.w3.org/TR/html5-diff/#absent-attributes HTML5 differences from HTML4, 3.6 Absent Attributes]: "<code>scope</code> attribute on <code>td</code>" will be deprecated in HTML 5. To prepare for the change we should use solely <code>scope</code> attribute on <code>th</code>.</ref><ref name="H63" group="WCAG">[http://www.w3.org/TR/2008/NOTE-WCAG20-TECHS-20081211/H63.html "H63: Using the scope attribute to associate header cells and data cells in data tables"], accessibility level: A</ref>
=== Layout of table headers ===
As can be seen in the example above, row headers are formatted by default as bold, centered and with a darker background. This is the common behavior across the Internet, and the default rendering in most browsers. In some circumstances it might be desirable to apply a style customized for a specific case. The class <code>plainrowheaders</code> will apply left-aligned and normal-weight formatting so that editors do not feel the need to override the header formatting with inline CSS declarations for each cell.<ref group="note">See the discussions at MediaWiki talk:Common.css [//en.wikipedia.org/w/index.php?title=MediaWiki_talk:Common.css&diff=prev&oldid=395578619#some_wikitable_ideas some wikitable ideas] and [//en.wikipedia.org/w/index.php?title=MediaWiki_talk:Common.css&diff=prev&oldid=395578619#Bold_row_headers bold row headers].</ref> Used by itself, <code>plainrowheaders</code> will make headers appear similar to unmodified data cells, except for the darker background.
To use <code>plainrowheaders</code>, place it (like <code>wikitable</code>) in the <code>class
<div style="display: inline-table;">
'''Wikitext:'''
<syntaxhighlight lang="wikitext">
{| class="wikitable plainrowheaders"
|-
! scope="col" | column header 1
! scope="col" | column header 2
|-
! scope="row" style="font-size: larger;" | row header
| data
|}
</syntaxhighlight>
</div>
<div style="display: inline-table;">
'''Produces:'''
{| class="wikitable plainrowheaders"
|-
! scope="col" | column header 1
! scope="col" | column header 2
|-
! scope="row" style="font-size: larger;" | row header
| data
|}
</div>
== Proper table captions and summaries ==
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Table markup provides for both ''captions'' and ''summaries'', both of great utility for making tables accessible. The caption provides a descriptive heading for the table and the summary provides a "nutshell" of its content. If you like, you can think of them as analogous, respectively, to a journal paper's title and its abstract.
=== Caption ===
* Priority: high (accessibility level: A)
* Difficulty: easy (the syntax is fairly simple and already in use; the layout slightly changes users' habits)
All data tables need a table ''caption'' that succinctly describes what the table is about.<ref name="H39" group="WCAG" /> It plays the role of a table heading, and is recommended as a best practice.<ref name="WebAccessibility 415">{{cite web |title=Ensure table captions are provided explicitly |at="Best Practices" section |author=<!--Staff writer(s); no by-line.--> |work=Accessibility Management Platform (AMP) |year=2015 |publisher=SSB BART Group |___location=San Francisco, California |url= https://www.webaccessibility.com/best_practices.php?best_practice_id=415 |accessdate=13 July 2015}} GSA Schedule 70. Cites multiple standards besides WCAG, including: JIS X 8341-3: 2004 - Technical Standards Subpart 5; KWCAG; 47 CFR 14. Advanced Communication Services, §14.21 Performance Objectives; HHS HTML 508 Checklist; and US Telecommunications Act Accessibility Guidelines 1193.41–43.</ref> You would usually need some kind of heading or description introducing a new table anyway, and this is what the caption feature exists for.
A temporary case for not using the <code>|+</code> caption is in certain situations when using a [[Help:Table/Advanced#Collapsible tables|collapsible table]]. {{As of|2010|09}}, the {{nowrap|"[hide]" / "[show]"}} collapse control has to be inside a table header (until the collapsibility script is improved), and it must be large enough to contain it. If the table has no header, or only a very small header, a common solution has been to put the caption text in a table header to which the collapse controller may attach.{{clarify|date=July 2015|reason=Has this problem been resolved yet? It's been almost 5 years.}}
Example of a proper caption from [[Special:PermanentLink/
{| class="wikitable sortable plainrowheaders"
|+ List of Bell's television appearances and roles
|-
! scope="col" | Year
! scope="col" | Title
! scope="col" | Role
! scope="col" class="unsortable" | Notes
|-
| 1987–1988
! scope="row" | ''{{sortname|The|Equalizer|The Equalizer (1985 TV series)}}''
| {{hlist|Cronin/Weber<!--Actual Screen Cred from "Mission: McCall", verbatim (One is an Alias)-->, Deputy Secretary<!--Day of the Covenant-->}}
|
|-
| 1989
! scope="row" | ''[[Perfect Witness]]''
| Dillon
| [[
|-
| 1990
! scope="row" | ''[[Alien Nation (TV series)|Alien Nation]]''
| Brian Knox / Dr. Death
| Episode: "[[Alien Nation (TV series)#ep18|Crossing the Line]]"
|}
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* Difficulty: medium (requires large changes to tables, editors seem reluctant to split tables, needs more testing and feedback)
Do not place column headers in the middle of a table to visually separate the table.
In most cases, the easier solution is to split the table into several sub-tables with explanatory sub-headings (second example).
=== Column headers: bad example ===
From [[Special:Redirect/revision/
{| class="wikitable" style="
|-
! Year
! Competition
! Venue
! Position
! Notes
|-
! colspan="5" | Representing {{URS}}
|-
| 1985
| [[1985 European Athletics Junior Championships|European Junior Championships]]
| [[Cottbus]], [[East Germany]]
|
|
|-
| 1986
| [[1986 World Junior Championships in Athletics|World Junior Championships]]
| [[Athens, Greece]]
|
|
|-
| 1990
| [[1990 European Championships in Athletics|European Championships]]
| [[Split (city)|Split]], [[Yugoslavia]]
| 4th
| [[1990 European Athletics Championships – Men's discus throw|63.72 m]]
|-
! colspan="5" | Representing {{BLR}}
|-
| 1993
| [[1993 World Championships in Athletics|World Championships]]
| [[Stuttgart, Germany]]
| 7th
| [[1993 World Championships in Athletics – Men's discus throw|61.64 m]]
|-
| rowspan="2" | 1995
| [[1995 World Championships in Athletics|World Championships]]
| [[Gothenburg]], [[Sweden]]
|
| [[1995 World Championships in Athletics – Men's discus throw|65.88 m]]
|-
| [[1995 IAAF Grand Prix Final|IAAF Grand Prix Final]]
| [[Monte Carlo]], Monaco
| 4th
|
|}
Line 178 ⟶ 210:
| 1986
| [[Athens, Greece]]
| style="background-color: #
|
|-
Line 205 ⟶ 237:
| rowspan="2" | 1995
| [[Gothenburg]], [[Sweden]]
| style="background-color: #
| [[1995 World Championships in Athletics – Men's discus throw|65.88 m]]
|-
Line 237 ⟶ 269:
| {{URS}}
| [[Athens, Greece]]
| style="background-color: #
|
|-
Line 258 ⟶ 290:
| {{BLR}}
| [[Gothenburg]], [[Sweden]]
| style="background-color: #
| [[1995 World Championships in Athletics – Men's discus throw|65.88 m]]
|-
Line 270 ⟶ 302:
== Complex tables ==
In contrast with simple tables, which only have
<div style="display: inline-table;">
'''Wikitext:'''
<syntaxhighlight lang="wikitext">
{| class="wikitable"
|-
! scope="col" rowspan="2" | column header 1
! scope="col" rowspan="2" | column header 2
! scope="colgroup" colspan="2" | column header group
|-
! scope="col" | column header 3
! scope="col" | column header 4
|-
! scope="rowgroup" rowspan="2" | row header group
! scope="row" | row header 1
| data || data
|-
! scope="row" | row header 2
| data || data
|-
! scope="row" colspan="2" | row header 3
| data || data
|}
</syntaxhighlight>
</div>
<div style="display: inline-table;">
'''Produces:'''
{| class="wikitable"
|-
! scope="col" rowspan="2" | column header 1
! scope="col" rowspan="2" | column header 2
! scope="colgroup" colspan="2" | column header group
|-
! scope="col" | column header 3
! scope="col" | column header 4
|-
! scope="rowgroup" rowspan="2" | row header group
! scope="row" | row header 1
| data || data
|-
! scope="row" | row header 2
| data || data
|-
! scope="row" colspan="2" | row header 3
| data || data
|}
</div>
For tables with headers that are more complex, it is recommended to simplify the table or split it up into smaller tables. When this isn't possible, you have to associate each cell to their respective header(s) using the <code>id</code> and <code>headers</code> attributes instead of <code>scope</code>. On the headers, set the <code>id</code> to an unspaced value that is unique on the page. On the cells that are described by headers, set the "headers" to a spaced list of the describing "id" values in an order that a screen reader should read them.<ref name="H43" group="WCAG">[https://www.w3.org/TR/2008/NOTE-WCAG20-TECHS-20081211/H43.html "H43: Using id and headers attributes to associate data cells with header cells in data tables"], accessibility level: A</ref> For example, the following markup has the "Company" header describing the "ABC" company (<code>! id="col1" | Company</code> and <code>| headers="col1" | ABC</code>).
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Below is an example of a complex table with headers that aren't visually clear, but uses <code>id</code> and <code>headers</code> instead of <code>scope</code> to associate column and row headers to individual cells. Again, it is recommended to simplify the table so headers are visually clear by splitting it into a "d" and "e" table if possible where the text in the "d" and "e" cells are moved to each table's caption.
<div style="display: inline-table;">
'''Wikitext:'''
<syntaxhighlight lang="wikitext">
{| class="wikitable"
|-
Line 304 ⟶ 385:
| headers="e c z" | e c z
|}
</syntaxhighlight
</div>
<div style="display: inline-table;">
'''Produces:'''
{| class="wikitable"
|-
Line 331 ⟶ 416:
| headers="e c z" | e c z
|}
</div>
== Images and color ==
Line 351 ⟶ 436:
* Difficulty: medium (needs testing and feedback for a precise rating)
Colors inside a table should meet the requirements for [[Wikipedia:Manual of Style (accessibility)#Color|color]].
* Color contrast – measured by the free [https://www.paciellogroup.com/resources/contrastanalyser/ Color Contrast Analyser] – needs to be sufficient.
* A very simple tool that can be helpful for choosing contrasting colours is [https://colororacle.org/ Color Oracle], a "free color blindness simulator for Windows, Mac and Linux".
But more importantly, information should not be conveyed by color alone. Information should also be available textually. A footnote or a textual sign<ref group="note">But avoid [[Unicode]] characters, per [[Wikipedia:Manual of Style (accessibility)#Text]]. See also [//en.wikipedia.org/w/index.php?title=User_talk:Bamse&diff=385470117&oldid=385349107 Graham87's explanation] in the context of a [//en.wikipedia.org/w/index.php?title=Wikipedia%3AFeatured_list_candidates%2FList_of_National_Treasures_of_Japan_%28crafts%3A_swords%29%2Farchive1&action=historysubmit&diff=385510315&oldid=385430878 featured list candidate.]</ref> can also be used to show a cell has a particular meaning.
Line 360 ⟶ 445:
From [//en.wikipedia.org/w/index.php?title=Fiscal_year&oldid=384026890#Chart_of_Different_Fiscal_Years Fiscal calendar#Chart of Different Fiscal Years]:
{| class="wikitable collapsible" style="width: 100%;"
|+ By country
|-
! width="100px" | Country
! width="100px" | Purpose
! width="20px" | J
! width="20px" | F
! width="20px" | M
! width="20px" | A
! width="20px" | M
! width="20px" | J
! width="20px" | J
! width="20px" | A
! width="20px" | S
! width="20px" | O
! width="20px" | N
! width="20px" | D
! width="20px" | J
! width="20px" | F
! width="20px" | M
! width="20px" | A
! width="20px" | M
! width="20px" | J
! width="20px" | J
! width="20px" | A
! width="20px" | S
! width="20px" | O
! width="20px" | N
! width="20px" | D
|-
| colspan="2" | [[Australia]]
|
|
Line 397 ⟶ 482:
|
|
| colspan="12" style="background: #
|
|
Line 404 ⟶ 489:
|
|
|-
| colspan="2" | [[Canada]]
|
|
|
| colspan="12" style="background: #
|
|
Line 455 ⟶ 540:
! scope="col" style="width: 3%;" | {{abbr|N|November}}
! scope="col" style="width: 3%;" | {{abbr|D|December}}
|-
! scope="row" | [[Australia]]
|
Line 464 ⟶ 549:
|
|
| style="background: #
| style="background: #
| style="background: #
| style="background: #
| style="background: #
| style="background: #
| style="background: #
| style="background: #
| style="background: #
| style="background: #
| style="background: #
| style="background: #
|
|
Line 482 ⟶ 567:
|
|
|-
! scope="row" | [[Canada]]
|
Line 488 ⟶ 573:
|
|
| style="background: #
| style="background: #
| style="background: #
| style="background: #
| style="background: #
| style="background: #
| style="background: #
| style="background: #
| style="background: #
| style="background: #
| style="background: #
| style="background: #
|
|
Line 540 ⟶ 625:
! scope="col" style="width: 3%;" | {{abbr|N|November}}
! scope="col" style="width: 3%;" | {{abbr|D|December}}
|-
! scope="row" | [[Australia]]
|
Line 549 ⟶ 634:
|
|
| colspan="12" style="background: #
|
|
Line 556 ⟶ 641:
|
|
|-
! scope="row" | [[Canada]]
|
Line 562 ⟶ 647:
|
|
| colspan="12" style="background: #
|
|
Line 629 ⟶ 714:
In the following example, nested tables are used to display sub-tables of varying cell heights:
<div style="display: inline-table;">
'''Wikitext:'''
<syntaxhighlight lang="wikitext">
{| class="wikitable"
|
Line 642 ⟶ 730:
|
{| class="wikitable"
|
|-
| Insert 3down
Line 653 ⟶ 741:
|}
|}
</syntaxhighlight>
</div>
<div style="display: inline-table;">
'''Produces:'''
{| class="wikitable"
|
Line 668 ⟶ 759:
|
{| class="wikitable"
|
|-
| Insert 3down
Line 679 ⟶ 770:
|}
|}
</div>
By comparison, using rowspan would not only need careful juggling of the positions and values but would break normal flow, splitting up each data subset and even causing Insert 3down and Insert 4down to be read in the wrong order:
<div style="display: inline-table;">
'''Wikitext:'''
<syntaxhighlight lang="wikitext">
{| class="wikitable"
| Insert 1up
| rowspan="4" | full height
| rowspan="3" | Insert 3up<br> <br>Tall cell here
| rowspan="2" | Insert 4up
|-
| rowspan="3" | Insert 1down:<br> <br>Taller than insert 1up
|-
| rowspan="2" | Insert 4down<br>Same as above
|-
| Insert 3down
|}
</syntaxhighlight>
</div>
<div style="display: inline-table;">
'''Produces:'''
{| class="wikitable"
| Insert 1up
| rowspan="4" | full height
| rowspan="3" | Insert 3up<br> <br>Tall cell here
| rowspan="2" | Insert 4up
|-
| rowspan="3" | Insert 1down:<br> <br>Taller than insert 1up
|-
| rowspan="2" | Insert 4down<br>Same as above
|-
| Insert 3down
|}
</div>
CSS also has table display properties which can be applied to other elements such as divs, and could be used to create the layout with correct normal flow. But it requires a custom stylesheet defining the various classes of substitute entity. Moreover, it breaks the formal separation of HTML structure vs. CSS styling by using the styling language to render the correct structure onscreen. It is unnecessary and is not recommended.
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[[Category:Wikipedia Manual of Style (accessibility)|Data tables tutorial]]
[[Category:Wikipedia essays and information pages about the Manual of Style]]
[[Category:Wikipedia tables]]
[[ja:Wikipedia:スタイルマニュアル (表)]]
| |||