If the a element has an href attribute,
then it represents a hyperlink (a hypertext anchor) labeled by its
contents.
If the a element has no href attribute,
then the element represents a placeholder for where a link might otherwise have been
placed, if it had been relevant, consisting of just the element's contents.
If a site uses a consistent navigation toolbar on every page, then the link that would
normally link to the page itself could be marked up using an a element:
The href, target, download, and
attributes affect what happens when users follow
hyperlinks or download hyperlinks created using
the a element. The rel, hreflang, and type
attributes may be used to indicate to the user the likely nature of the target resource before the
user follows the link.
Abort these steps without following the hyperlink.
If the target of the click event is an img
element with an ismap attribute specified, then server-side
image map processing must be performed, as follows:
If the click event was a real pointing-device-triggered
click event on the img element, then let x be the distance in CSS pixels from the left edge of the image's left border,
if it has one, or the left edge of the image otherwise, to the location of the click, and let
y be the distance in CSS pixels from the top edge of the image's top
border, if it has one, or the top edge of the image otherwise, to the location of the click.
Otherwise, let x and y be zero.
Let the hyperlink suffix be a U+003F QUESTION MARK character, the
value of x expressed as a base-ten integer using ASCII digits,
a "," (U+002C) character, and the value of y expressed as a base-ten
integer using ASCII digits.
Finally, the user agent must follow the
hyperlink or download the hyperlink created by
the a element, as determined by the download attribute and any expressed user preference. If
the steps above defined a hyperlink suffix, then take that into account when following
or downloading the hyperlink.
The IDL attributes download,
target,
rel, rev, hreflang, and type, must reflect the respective content
attributes of the same name.
The IDL attribute relList must
reflect the rel content attribute.
The text IDL attribute, on getting, must return the
same value as the textContent IDL attribute on the element, and on setting, must act
as if the textContent IDL attribute on the element had been set to the new value.
The a element also supports the URLUtils interface. [URL]
When the element is created, and whenever the element's href content attribute is set, changed, or removed, the user
agent must invoke the element's URLUtils interface's set the input algorithm with the value of the href content attribute, if any, or the empty string otherwise,
as the given value.
When the element's URLUtils interface invokes its update steps with a string value, the user
agent must set the element's href content attribute to
the string value.
The a element may be wrapped around entire paragraphs, lists, tables, and so
forth, even entire sections, so long as there is no interactive content within (e.g. buttons or
other links). This example shows how this can be used to make an entire advertising block into a
link:
The em element represents stress emphasis of its contents.
The level of stress that a particular piece of content has is given by its number of ancestor
em elements.
The placement of stress emphasis changes the meaning of the sentence. The element thus forms an
integral part of the content. The precise way in which stress is used in this way depends on the
language.
These examples show how changing the stress emphasis changes the meaning. First, a general
statement of fact, with no stress:
Cats are cute animals.
By emphasizing the first word, the statement implies that the kind of animal under discussion
is in question (maybe someone is asserting that dogs are cute):
Cats are cute animals.
Moving the stress to the verb, one highlights that the truth of the entire sentence is in
question (maybe someone is saying cats are not cute):
Cats are cute animals.
By moving it to the adjective, the exact nature of the cats is reasserted (maybe someone
suggested cats were mean animals):
Cats are cute animals.
Similarly, if someone asserted that cats were vegetables, someone correcting this might
emphasize the last word:
Cats are cute animals.
By emphasizing the entire sentence, it becomes clear that the speaker is fighting hard to get
the point across. This kind of stress emphasis also typically affects the punctuation, hence the
exclamation mark here.
Cats are cute animals!
Anger mixed with emphasizing the cuteness could lead to markup such as:
Cats are cute animals!
The em element isn't a generic "italics" element. Sometimes, text is intended to
stand out from the rest of the paragraph, as if it was in a different mood or voice. For this,
the i element is more appropriate.
The em element also isn't intended to convey importance; for that purpose, the
strong element is more appropriate.
The strong element represents strong importance, seriousness, or
urgency for its contents.
Importance: The strong element can be used in a heading, caption,
or paragraph to distinguish the part that really matters from other parts of the that might be
more detailed, more jovial, or merely boilerplate.
For example, the first word of the previous paragraph is marked up with
strong to distinguish it from the more detailed text in the rest of the
paragraph.
Seriousness: The strong element can be used to mark up a warning
or caution notice.
Urgency: The strong element can be used to denote contents that
the user needs to see sooner than other parts of the document.
The relative level of importance of a piece of content is given by its number of ancestor
strong elements; each strong element increases the importance of its
contents.
Changing the importance of a piece of text with the strong element does not change
the meaning of the sentence.
Here, the word "chapter" and the actual chapter number are mere boilerplate, and the actual
name of the chapter is marked up with strong:
Chapter 1: The Praxis
In the following example, the name of the diagram in the caption is marked up with
strong, to distinguish it from boilerplate text (before) and the description
(after):
Figure 1. Ant colony dynamics. The ants in this colony are
affected by the heat source (upper left) and the food source (lower right).
In this example, the heading is really "Flowers, Bees, and Honey", but the author has added a
light-hearted addition to the heading. The strong element is thus used to mark up
the first part to distinguish it from the latter part.
Flowers, Bees, and Honey and other things I don't understand
Here is an example of a warning notice in a game, with the
various parts marked up according to how important they are:
Warning. This dungeon is dangerous.
Avoid the ducks. Take any gold you find.
Do not take any of the diamonds,
they are explosive and will destroy anything within
ten meters. You have been warned.
In this example, the strong element is used to denote the part of the text that
the user is intended to read first.
The small element represents side comments such as small print.
Small print typically features disclaimers, caveats, legal restrictions, or
copyrights. Small print is also sometimes used for attribution, or for satisfying licensing
requirements.
The small element does not "de-emphasize" or lower the importance of
text emphasized by the em element or marked as important with the strong
element. To mark text as not emphasized or important, simply do not mark it up with the
em or strong elements respectively.
The small element should not be used for extended spans of text, such as multiple
paragraphs, lists, or sections of text. It is only intended for short runs of text. The text of a
page listing terms of use, for instance, would not be a suitable candidate for the
small element: in such a case, the text is not a side comment, it is the main content
of the page.
In this example, the small element is used to indicate that value-added tax is
not included in a price of a hotel room:
Single room
199 € breakfast included, VAT not included
Double room
239 € breakfast included, VAT not included
In this second example, the small element is used for a side comment in an
article.
Example Corp today announced record profits for the
second quarter (Full Disclosure: Foo News is a subsidiary of
Example Corp), leading to speculation about a third quarter
merger with Demo Group.
This is distinct from a sidebar, which might be multiple paragraphs long and is removed from
the main flow of text. In the following example, we see a sidebar from the same article. This
sidebar also has small print, indicating the source of the information in the sidebar.
In this last example, the small element is marked as being important
small print.
Continued use of this service will result in a kiss.
The cite element represents a reference to a creative work. It must include the
title of the work or the name of the author(person, people or organization) or an URL reference, which may be in an abbreviated form as per the conventions used for the addition of citation metadata.
Creative works include a book, a paper, an essay, a poem, a score, a song, a script, a film,
a TV show, a game, a sculpture, a painting, a theatre production, a play, an opera, a musical, an exhibition,
a legal case report, a web site, a web page, a blog post or comment, a forum post or comment, a tweet, a written or oral statement, etc.
Here is an example of the author of a quote referenced using the cite element:
In the words of Charles Bukowski -
An intellectual says a simple thing in a hard way. An artist says a hard thing in a simple way.
This second example identifies the author of a tweet by referencing the authors name using the cite element:
Unfortunately I don't think adding names back into the definition of cite
solves the problem: of the 12 blockquote examples in
Examples of block quote metadata,
there's not even one that's just a person’s name.
A subset of the problem, maybe…
Another common use for the cite element is to reference the URL
of a search result, as in this example:
Quotation punctuation (such as quotation marks) that is quoting
the contents of the element must not appear immediately before,
after, or inside q elements; they will be inserted into
the rendering by the user agent.
Content inside a q element must be quoted from
another source, whose address, if it has one, may be cited in the
cite attribute. The
source may be fictional, as when quoting characters in a novel or
screenplay.
If the cite attribute is present, it must be a valid URL
potentially surrounded by spaces. To obtain the corresponding citation
link, the value of the attribute must be resolved relative to
the element. User agents may allow users to follow such citation links, but they are
primarily intended for private use (e.g. by server-side scripts collecting statistics about a
site's use of quotations), not for readers.
The q element must not be used in place of quotation
marks that do not represent quotes; for example, it is inappropriate
to use the q element for marking up sarcastic
statements.
The use of q elements to mark up quotations is
entirely optional; using explicit quotation punctuation without
q elements is just as correct.
Here is a simple example of the use of the q
element:
The man said Things that are impossible just take
longer. I disagreed with him.
Here is an example with both an explicit citation link in the
q element, and an explicit citation outside:
The W3C page About W3C says the W3C's
mission is To lead the
World Wide Web to its full potential by developing protocols and
guidelines that ensure long-term growth for the Web. I
disagree with this mission.
In the following example, the quotation itself contains a
quotation:
In Example One, he writes The man
said Things that are impossible just take longer. I
disagreed with him. Well, I disagree even more!
In the following example, quotation marks are used instead of
the q element:
His best argument was ❝I disagree❞, which
I thought was laughable.
In the following example, there is no quote — the
quotation marks are used to name a word. Use of the q
element in this case would be inappropriate.
The word "ineffable" could have been used to describe the disaster
resulting from the campaign's mismanagement.
Defining term: If the dfn element has a
title attribute, then
the exact value of that attribute is the term being defined.
Otherwise, if it contains exactly one element child node and no
child Text nodes, and that child
element is an abbr element with a title attribute, then the exact value
of that attribute is the term being defined. Otherwise, it
is the exact textContent of the dfn
element that gives the term being defined.
If the title attribute of the
dfn element is present, then it must contain only the
term being defined.
The title attribute
of ancestor elements does not affect dfn elements.
An a element that links to a dfn
element represents an instance of the term defined by the
dfn element.
In the following fragment, the term "Garage Door Opener" is
first defined in the first paragraph, then used in the second. In
both cases, its abbreviation is what is actually displayed.
The GDO
is a device that allows off-world teams to open the iris.
Teal'c activated his GDO
and so Hammond ordered the iris to be opened.
With the addition of an a element, the reference
can be made explicit:
The id=gdo>GDO
is a device that allows off-world teams to open the iris.
Teal'c activated his GDO
and so Hammond ordered the iris to be opened.
The abbr element represents an abbreviation or acronym, optionally
with its expansion. The title attribute may be
used to provide an expansion of the abbreviation. The attribute, if specified, must contain an
expansion of the abbreviation, and nothing else.
The paragraph below contains an abbreviation marked up with the abbr element.
This paragraph defines the term "Web Hypertext Application
Technology Working Group".
The WHATWG
is a loose unofficial collaboration of Web browser manufacturers and
interested parties who wish to develop new technologies designed to
allow authors to write and deploy Applications over the World Wide
Web.
An alternative way to write this would be:
The Web Hypertext Application Technology
Working Group (WHATWG)
is a loose unofficial collaboration of Web browser manufacturers and
interested parties who wish to develop new technologies designed to
allow authors to write and deploy Applications over the World Wide
Web.
This paragraph has two abbreviations. Notice how only one is defined; the other, with no
expansion associated with it, does not use the abbr element.
The
WHATWG
started working on HTML5 in 2004.
This paragraph links an abbreviation to its definition.
The WHATWG
community does not have much representation from Asia.
This paragraph marks up an abbreviation without giving an expansion, possibly as a hook to
apply styles for abbreviations (e.g. smallcaps).
Philip` and Dashiva both denied that they were going to
get the issue counts from past revisions of the specification to
backfill the WHATWG issue graph.
If an abbreviation is pluralized, the expansion's grammatical number (plural vs singular) must
match the grammatical number of the contents of the element.
Here the plural is outside the element, so the expansion is in the singular:
Two WGs worked on
this specification: the WHATWG and the
HTMLWG.
Here the plural is inside the element, so the expansion is in the plural:
Two WGs worked on
this specification: the WHATWG and the
HTMLWG.
Abbreviations do not have to be marked up using this element. It is expected to be useful in
the following cases:
Abbreviations for which the author wants to give expansions, where using the
abbr element with a title attribute is an
alternative to including the expansion inline (e.g. in parentheses).
Abbreviations that are likely to be unfamiliar to the document's readers, for which authors
are encouraged to either mark up the abbreviation using an abbr element with a title attribute or include the expansion inline in the text the first
time the abbreviation is used.
Abbreviations whose presence needs to be semantically annotated, e.g. so that they can be
identified from a style sheet and given specific styles, for which the abbr element
can be used without a title attribute.
Providing an expansion in a title attribute once
will not necessarily cause other abbr elements in the same document with the same
contents but without a title attribute to behave as if they had
the same expansion. Every abbr element is independent.
The data element represents its
contents, along with a machine-readable form of those contents in
the value attribute.
The value
attribute must be present. Its value must be a representation of the
element's contents in a machine-readable format.
When the value is date- or time-related, the more
specific time element can be used instead.
The element can be used for several purposes.
When combined with microformats or
microdata,
the element serves to provide both a machine-readable
value for the purposes of data processors, and a human-readable value
for the purposes of rendering in a Web browser. In this case, the
format to be used in the value
attribute is determined by the microformats or microdata
vocabulary in use.
The element can also, however, be used in conjunction with
scripts in the page, for when a script has a literal value to store
alongside a human-readable value. In such cases, the format to be
used depends only on the needs of the script. (The data-* attributes can also be useful in
such situations.)
The value IDL
attribute must reflect the content attribute of the
same name.
The time element represents its contents, along with a
machine-readable form of those contents in the datetime
attribute. The kind of content is limited to various kinds of dates, times, time-zone offsets, and
durations, as described below.
The datetime attribute may be present. If
present, its value must be a representation of the element's contents in a machine-readable
format.
A time element that does not have a datetime content attribute must not have any element
descendants.
The datetime value of a time element is the value of the element's
datetime content attribute, if it has one, or the
element's textContent, if it does not.
The datetime value of a time element must match one of the following
syntaxes.
Times with dates but without a time zone offset are useful for specifying events
that are observed at the same specific time in each time zone, throughout a day. For example,
the 2020 new year is celebrated at 2020-01-01 00:00 in each time zone, not at the same precise
moment across all time zones. For events that occur at the same time across all time zones, for
example a videoconference meeting, a valid global date and time string is likely
more useful.
For times without dates (or times referring to events that recur on multiple
dates), specifying the geographic location that controls the time is usually more useful than
specifying a time zone offset, because geographic locations change time zone offsets with
daylight savings time. In some cases, geographic locations even change time zone, e.g. when the
boundaries of those time zones are redrawn, as happened with Samoa at the end of 2011. There
exists a time zone database that describes the boundaries of time zones and what rules apply
within each such zone, known as the time zone database. [TZDATABASE]
Times with dates and a time zone offset are useful for specifying specific
events, or recurring virtual events where the time is not anchored to a specific geographic
location. For example, the precise time of an asteroid impact, or a particular meeting in a
series of meetings held at 1400 UTC every day, regardless of whether any particular part of the
world is observing daylight savings time or not. For events where the precise time varies by the
local time zone offset of a specific geographic location, a valid floating date and time
string combined with that geographic location is likely more useful.
Many of the preceding valid syntaxes describe "floating" date and/or time values
(they do not include a time-zone offset). Care is needed when
converting floating time values to or from global ("incremental") time values (e.g., JavaScript's
Date object). In many cases, an implicit time-of-day and time zone are used in the conversion and
may result in unexpected changes to the value of the date itself.
[TIMEZONES]
The machine-readable equivalent of the element's contents must be obtained from the
element's datetime value by using the following algorithm:
If the element's datetime value consists of only ASCII digits,
at least one of which is not "0" (U+0030), then the machine-readable equivalent is the
base-ten interpretation of those digits, representing a year; abort these steps.
The algorithms referenced above are intended to be designed such that for any
arbitrary string s, only one of the algorithms returns a value. A more
efficient approach might be to create a single algorithm that parses all these data types in one
pass; developing such an algorithm is left as an exercise to the reader.
The dateTime IDL attribute must
reflect the element's datetime content
attribute.
The time element can be used to encode dates, for example in microformats. The
following shows a hypothetical way of encoding an event using a variant on hCalendar that uses
the time element:
Here, a fictional microdata vocabulary based on the Atom vocabulary is used with the
time element to mark up a blog post's publication date.
Big tasks
Today, I went out and bought a bike for my kid.
In this example, another article's publication date is marked up using time, this
time using the schema.org microdata vocabulary:
Small tasks
I put a bike bell on his bike.
In the following snippet, the time element is used to encode a date in the
ISO8601 format, for later processing by a script:
Our first date was .
In this second snippet, the value includes a time:
We stopped talking at .
A script loaded by the page (and thus privy to the page's internal convention of marking up
dates and times using the time element) could scan through the page and look at all
the time elements therein to create an index of dates and times.
For example, this element conveys the string "Tuesday" with the additional semantic that the
12th of November 2011 is the meaning that corresponds to "Tuesday":
Today is .
In this example, a specific time in the Pacific Standard Time timezone is specified:
The code element represents a fragment of computer code. This could
be an XML element name, a file name, a computer program, or any other string that a computer would
recognize.
There is no formal way to indicate the language of computer code being marked up. Authors who
wish to mark code elements with the language used, e.g. so that syntax highlighting
scripts can use the right rules, can use the class attribute, e.g.
by adding a class prefixed with "language-" to the element.
The following example shows how the element can be used in a paragraph to mark up element
names and computer code, including punctuation.
The code element represents a fragment of computer
code.
When you call the activate() method on the
robotSnowman object, the eyes glow.
The example below uses the begin keyword to indicate
the start of a statement block. It is paired with an end
keyword, which is followed by the . punctuation character
(full stop) to indicate the end of the program.
The following example shows how a block of code could be marked up using the pre
and code elements.
var i: Integer;
begin
i := 1;
end.
A class is used in that example to indicate the language used.
The var element represents a variable.
This could be an actual variable in a mathematical expression or
programming context, an identifier representing a constant, a symbol
identifying a physical quantity, a function parameter, or just be a
term used as a placeholder in prose.
In the paragraph below, the letter "n" is being used as a
variable in prose:
If there are n pipes leading to the ice
cream factory then I expect at leastn
flavors of ice cream to be available for purchase!
For mathematics, in particular for anything beyond the simplest
of expressions, MathML is more appropriate. However, the
var element can still be used to refer to specific
variables that are then mentioned in MathML expressions.
In this example, an equation is shown, with a legend that
references the variables in the equation. The expression itself is
marked up with MathML, but the variables are mentioned in the
figure's legend using var.
Using Pythagoras' theorem to solve for the hypotenuse a of
a triangle with sides b and c
Here, the equation describing mass-energy equivalence is used in a sentence, and the
var element is used to mark the variables and constants in that equation:
Then he turned to the blackboard and picked up the chalk. After a few moment's
thought, he wrote E = mc2. The teacher
looked pleased.
This example shows the samp element being used
inline:
The computer said Too much cheese in tray
two but I didn't know what that meant.
This second example shows a block of sample output. Nested samp and
kbd elements allow for the styling of specific elements of the sample output using a
style sheet. There's also a few parts of the samp that are annotated with even more
detailed markup, to enable very precise styling. To achieve this, span elements are
used.
jdoe@mowmow:~$ssh demo.example.com
Last login: Tue Apr 12 09:10:17 2005 from mowmow.example.com on pts/1
Linux demo 2.6.10-grsec+gg3+e+fhs6b+nfs+gr0501+++p3+c4a+gr2b-reslog-v6.189 #1 SMP Tue Feb 1 11:22:36 PST 2005 i686 unknown
jdoe@demo:~$_
The kbd element represents user input (typically keyboard input,
although it may also be used to represent other input, such as voice commands).
When the kbd element is nested inside a samp element, it represents
the input as it was echoed by the system.
When the kbd element contains a samp element, it represents
input based on system output, for example invoking a menu item.
When the kbd element is nested inside another kbd element, it
represents an actual key or other single unit of input as appropriate for the input mechanism.
Here the kbd element is used to indicate keys to press:
To make George eat an apple, press Shift+F3
In this second example, the user is told to pick a particular menu item. The outer
kbd element marks up a block of input, with the inner kbd elements
representing each individual step of the input, and the samp elements inside them
indicating that the steps are input based on something being displayed by the system, in this
case menu labels:
To make George eat an apple, select
File|Eat Apple...
Such precision isn't necessary; the following is equally fine:
To make George eat an apple, select File | Eat Apple...
These elements must be used only to mark up typographical conventions with specific meanings,
not for typographical presentation for presentation's sake. For example, it would be inappropriate
for the sub and sup elements to be used in the name of the LaTeX
document preparation system. In general, authors should use these elements only if the
absence of those elements would change the meaning of the content.
In certain languages, superscripts are part of the typographical conventions for some
abbreviations.
The most beautiful women are
Mlle Gwendoline and
Mme Denise.
The sub element can be used inside a var element, for variables that
have subscripts.
Here, the sub element is used to represent the subscript that identifies the
variable in a family of variables:
The coordinate of the ith point is
(xi, yi).
For example, the 10th point has coordinate
(x10, y10).
Mathematical expressions often use subscripts and superscripts. Authors are encouraged to use
MathML for marking up mathematics, but authors may opt to use sub and
sup if detailed mathematical markup is not desired. [MATHML]
The i element represents a span of text in an alternate voice or
mood, or otherwise offset from the normal prose in a manner indicating a different quality of
text, such as a taxonomic designation, a technical term, an idiomatic phrase from another
language, transliteration, a thought, or a ship name in Western texts.
In the following example, a dream sequence is marked up using
i elements.
Raymond tried to sleep.
The ship sailed away on Thursday, he
dreamt. The ship had many people aboard, including a beautiful
princess called Carey. He watched her, day-in, day-out, hoping she
would notice him, but she never did.
Finally one night he picked up the courage to speak with
her—
Raymond woke with a start as the fire alarm rang out.
Authors can use the class attribute on the i
element to identify why the element is being used, so that if the style of a particular use (e.g.
dream sequences as opposed to taxonomic terms) is to be changed at a later date, the author
doesn't have to go through the entire document (or series of related documents) annotating each
use.
Authors are encouraged to consider whether other elements might be more applicable than the
i element, for instance the em element for marking up stress emphasis,
or the dfn element to mark up the defining instance of a term.
Style sheets can be used to format i elements, just like any other
element can be restyled. Thus, it is not the case that content in i elements will
necessarily be italicized.
The b element represents a span of text to which attention is being
drawn for utilitarian purposes without conveying any extra importance and with no implication of
an alternate voice or mood, such as key words in a document abstract, product names in a review,
actionable words in interactive text-driven software, or an article lede.
The following example shows a use of the b element to highlight key words without
marking them up as important:
The frobonitor and barbinator components are fried.
In the following example, objects in a text adventure are highlighted as being special by use
of the b element.
You enter a small room. Your sword glows
brighter. A rat scurries past the corner wall.
Six abandoned kittens have found an
unexpected new mother figure — a pet rabbit.
Veterinary nurse Melanie Humble took the three-week-old
kittens to her Aberdeen home.
[...]
As with the i element, authors can use the class
attribute on the b element to identify why the element is being used, so that if the
style of a particular use is to be changed at a later date, the author doesn't have to go through
annotating each use.
The b element should be used as a last resort when no other element is more
appropriate. In particular, headings should use the h1 to h6 elements,
stress emphasis should use the em element, importance should be denoted with the
strong element, and text marked or highlighted should use the mark
element.
The following would be incorrect usage:
WARNING! Do not frob the barbinator!
In the previous example, the correct element to use would have been strong, not
b.
Style sheets can be used to format b elements, just like any other
element can be restyled. Thus, it is not the case that content in b elements will
necessarily be boldened.
The u element represents a span of text with an unarticulated, though
explicitly rendered, non-textual annotation, such as labeling the text as being a proper name in
Chinese text (a Chinese proper name mark), or labeling the text as being misspelt.
In most cases, another element is likely to be more appropriate: for marking stress emphasis,
the em element should be used; for marking key words or phrases either the
b element or the mark element should be used, depending on the context;
for marking book titles, the cite element should be used; for labeling text with explicit textual annotations, the
ruby element should be used; for labeling ship names in Western texts, the
i element should be used.
The default rendering of the u element in visual presentations
clashes with the conventional rendering of hyperlinks (underlining). Authors are encouraged to
avoid using the u element where it could be confused for a hyperlink.
The mark element represents a run of text in one document marked or
highlighted for reference purposes, due to its relevance in another context. When used in a
quotation or other block of text referred to from the prose, it indicates a highlight that was not
originally present but which has been added to bring the reader's attention to a part of the text
that might not have been considered important by the original author when the block was originally
written, but which is now under previously unexpected scrutiny. When used in the main prose of a
document, it indicates a part of the document that has been highlighted due to its likely
relevance to the user's current activity.
This example shows how the mark element can be used to bring attention to a
particular part of a quotation:
Consider the following quote:
Look around and you will find, no-one's really
colour blind.
As we can tell from the spelling of the word,
the person writing this quote is clearly not American.
(If the goal was to mark the element as misspelt, however, the u element,
possibly with a class, would be more appropriate.)
Another example of the mark element is highlighting parts of a document that are
matching some search string. If someone looked at a document, and the server knew that the user
was searching for the word "kitten", then the server might return the document with one paragraph
modified as follows:
I also have some kittens who are visiting me
these days. They're really cute. I think they like my garden! Maybe I
should adopt a kitten.
In the following snippet, a paragraph of text refers to a specific part of a code
fragment.
The highlighted part below is where the error lies:
var i: Integer;
begin
i := 1.1;
end.
This is separate from syntax highlighting, for which span is more
appropriate. Combining both, one would get:
The highlighted part below is where the error lies:
vari: Integer;
begini := 1.1;
end.
This is another example showing the use of mark to highlight a part of quoted
text that was originally not emphasized. In this example, common typographic conventions have led
the author to explicitly style mark elements in quotes to render in italics.
She knew
Did you notice the subtle joke in the joke on panel 4?
I didn't want to believe. Of course
on some level I realized it was a known-plaintext attack. But I
couldn't admit it until I saw for myself.
(Emphasis mine.) I thought that was great. It's so pedantic, yet it
explains everything neatly.
Note, incidentally, the distinction between the em element in this example, which
is part of the original text being quoted, and the mark element, which is
highlighting a part for comment.
The following example shows the difference between denoting the importance of a span
of text (strong) as opposed to denoting the relevance of a span of text
(mark). It is an extract from a textbook, where the extract has had the parts
relevant to the exam highlighted. The safety warnings, important though they may be, are
apparently not relevant to the exam.
Wormhole Physics Introduction
A wormhole in normal conditions can be held open for a
maximum of just under 39 minutes. Conditions that can increase
the time include a powerful energy source coupled to one or both of
the gates connecting the wormhole, and a large gravity well (such as a
black hole).
Momentum is preserved across the wormhole. Electromagnetic
radiation can travel in both directions through a wormhole,
but matter cannot.
When a wormhole is created, a vortex normally forms.
Warning: The vortex caused by the wormhole opening will
annihilate anything in its path. Vortexes can be avoided when
using sufficiently advanced dialing technology.
An obstruction in a gate will prevent it from accepting a
wormhole connection.
The ruby element allows one or more spans of phrasing content to be marked with
ruby annotations. Ruby annotations are short runs of text presented alongside base text,
primarily used in East Asian typography as a guide for pronunciation or to include other
annotations. In Japanese, this form of typography is also known as furigana. Ruby text
can appear on either side, and sometimes both sides, of the base text, and it is possible to
control its position using CSS. A more complete introduction to ruby can be found in the
Use Cases & Exploratory Approaches for Ruby Markup document as well as in
CSS Ruby Module Level 1. [RUBY-UC][CSSRUBY]
The content model of ruby elements consists of one or more of the following
sequences:
One or more rt or rtc elements, each of which either immediately
preceded or followed by an rp elements.
The ruby, rb, rtc, and rt elements can be
used for a variety of kinds of annotations, including in particular (though by no means limited
to) those described below. For more details on Japanese Ruby in particular, and how to render
Ruby for Japanese, see Requirements for Japanese Text Layout. [JLREQ] The rp element can be used as fallback content when
ruby rendering is not supported.
Mono-ruby for individual base characters
Annotations (the ruby text) are associated individually with each ideographic character
(the base text). In Japanese this is typically hiragana or katakana characters used to
provide readings of kanji characters.
base
When no rb element is used, the base is implied, as above. But you can also
make it explicit. This can be useful notably for styling, or when consecutive bases are
to be treated as a group, as in the jukugo ruby example further down.
base
In the following example, notice how each annotation corresponds to a single base
character.
日本
語で書
いた作文です。
Ruby text interspersed in regular text provides structure akin to the following image:
This example can also be written as follows, using one ruby element with
two segments of base text and two annotations (one for each) rather than two
back-to-back ruby elements each with one base text segment and annotation
(as in the markup above):
日本語
で書
いた作文です。
Group ruby
Group ruby is often used where phonetic annotations don't map to discreet base
characters, or for semantic glosses that span the whole base text. For example, the word
"today" is written with the characters 今日, literally "this day". But it's pronounced きょう
(kyou), which can't be broken down into a "this" part and a "day" part. In typical
rendering, you can't split text that is annotated with group ruby; it has to wrap as a
single unit onto the next line. When a ruby text annotation maps to a base that
is comprised of more than one character, then that base is grouped.
The following group ruby:
Can be marked up as follows:
今日
Jukugo ruby
Jukugo refers to a Japanese compound noun, i.e. a word made up of more than one
kanji character. Jukugo ruby is a term that is used not to describe ruby
annotations over jukugo text, but rather to describe ruby with a behaviour slightly
different from mono or group ruby. Jukugo ruby is similar to mono ruby, in that there is
a strong association between ruby text and individual base characters, but the ruby text
is typically rendered as grouped together over multiple ideographs when they are on the
same line.
The distinction is captured in this example:
Which can be marked up as follows:
法華経
In this example, each rt element is paired with its respective
rb element, the difference with an interleaved
rb/rt approach being that the sequences of both base text and
ruby annotations are implicitly placed in common containers so that the grouping
information is captured.
For more details on
Jukugo Ruby
rendering, see Appendix F in the Requirements for Japanese Text Layout
and Use Case C: Jukugo ruby in the Use Cases & Exploratory Approaches for Ruby
Markup. [JLREQ][RUBY-UC]
Inline ruby
In some contexts, for instance when the font size or line height are too small for ruby
to be readable, it is desirable to inline the ruby annotation such that it appears in
parentheses after the text it annotates. This also provides a convenient fallback
strategy for user agents that do not support rendering ruby annotations.
Inlining takes grouping into account. For example, Tokyo is written with two kanji
characters, 東, which is pronounced とう, and 京, which is pronounced きょう. Each base
character should be annotated individually, but the fallback should be 東京(とうきょう) not
東(とう)京(きょう). This can be marked up as follows:
東京
Note that the above markup will enable the usage of parentheses when inlining for
browsers that support ruby layout, but for those that don't it will fail to provide
parenthetical fallback. This is where the rp element is useful. It can be
inserted into the above example to provide the appropriate fallback when ruby layout is
not supported:
東京
Text with both phonetic and semantic annotations (double-sided ruby)
Sometimes, ruby can be used to annotate a base twice.
In the following example, the Chinese word for San Francisco (旧金山, i.e. “old gold
mountain”) is annotated both using pinyin to give the pronunciation, and with the
original English.
Which is marked up as follows:
旧金山
In this example, a single base run of three base characters is annotated with three
pinyin ruby text segments in a first (implicit) container, and an rtc
element is introduced in order to provide a second single ruby text annotation
being the city's English name.
We can also revisit our jukugo example above with 上手 ("skill") to show how it can be
annotation in both kana and romaji phonetics while at the same time maintaining the
pairing to bases and annotation grouping information.
Which is marked up as follows:
上手
Text that is a direct child of the rtc element implicitly produces a ruby
text segment as if it were contained in an rt element. In this contrived
example, this is shown with some symbols that are given names in English and French with
annotations intended to appear on either side of the base symbol.
♥
Similarly, text directly inside a ruby element implicitly produces a ruby
base as if it were contained in an rb element, and rt children
of ruby are implicitly contained in an rtc container. In
effect, the above example is equivalent (in meaning, though not in the DOM it produces)
to the following:
♥☘✶
Within a ruby element, content is parcelled into a series of ruby segments. Each ruby
segment is described by:
Zero or more ruby bases, each of which is a DOM range that
may contain phrasing content or an rb element.
A base range, that is a DOM range including all the bases. This is the
ruby base container.
Zero or more ruby text containers which may
correspond to explicit rtc elements, or to sequences of rt
elements implicitly recognised as contained in an anonymous ruby text
container.
Each ruby text container is described by zero or more ruby text annotations each of which is a DOM range that may contain
phrasing content or an rt element, and an annotations range that is a range
including all the annotations for that container. A ruby text container is also
known (primarily in a CSS context) as a ruby annotation container.
Furthermore, a ruby element contains ignored ruby content. Ignored ruby content
does not form part of the document's semantics. It consists of some inter-element
whitespace and rp elements, the latter of which are used for legacy user
agents that do not support ruby at all.
Informally, the segmentation and categorisation algorithm below performs a simple set of
tasks. First it processes adjacent rb elements, text nodes, and non-ruby
elements into a list of bases. Then it processes any number of rtc elements or
sequences of rt elements that are considered to automatically map to an
anonymous ruby text container. Put together these data items form a ruby
segment as detailed in the data model above. It will continue to produce such segments
until it reaches the end of the content of a given ruby element. The complexity
of the algorithm below compared to this informal description stems from the need to support
an author-friendly syntax and being mindful of inter-element white space.
At any particular time, the segmentation and categorisation of content of a ruby element
is the result that would be obtained from running the following algorithm:
Let root be the ruby element for which the algorithm is
being run.
Let index be 0.
Let ruby segments be an empty list.
Let current bases be an empty list of DOM ranges.
Let current bases range be null.
Let current bases range start be null.
Let current annotations be an empty list of DOM ranges.
Let current annotations range be null.
Let current annotations range start be null.
Let current annotation containers be an empty list.
Let current automatic base nodes be an empty list of DOM Nodes.
Let current automatic base range start be null.
Process a ruby child: If index is equal to or greater than the number of
child nodes in root, then run the steps to commit a ruby segment,
return ruby segments, and abort these steps.
Let current child be the indexth node in root.
If current child is not a Text node and is not an
Element node, then increment index by one and jump to the step
labelled process a ruby child.
If current child is an rp element, then increment
index by one and jump to the step labelled process a ruby child. (Note
that this has the effect of including this element in any range that we are currently
processing. This is done intentionally so that misplaced rp can be
processed correctly; semantically they are ignored all the same.)
If current child is an rt element, then run these substeps:
If current annotations is empty, set current annotations range
start to the value of index.
Create a new DOM range whose start is the
boundary point (root,
index) and whose end is the boundary point (root, index plus
one), and append it at the end of current annotations.
Increment index by one and jump to the step labelled process a ruby
child.
If current child is an rtc element, then run these
substeps:
If peek child is an rt element, an
rtc element, or an rp element, then set
index to the value of lookahead index and jump to the step
labelled process a ruby child.
If current annotations is not empty or if current annotation
containers is not empty, then run the steps to commit a ruby segment.
If current child is an rb element, then run these substeps:
If current bases is empty, then set current bases range start to
the value of index.
Create a new DOM range whose start is the
boundary point (root,
index) and whose end is the boundary point (root, index plus
one), and append it at the end of current bases.
Increment index by one and jump to the step labelled process a ruby
child.
If current automatic base nodes is empty, set current automatic base range
start to the value of index.
Append current child at the end of current automatic base nodes.
Increment index by one and jump to the step labelled process a ruby
child.
When the steps above say to commit a ruby segment, it means to run the
following steps at that point in the algorithm:
Create a new ruby segment. It is described by a list of bases set to
current bases, a base DOM range set to current bases range, and a
list of ruby annotation containers
that are the current annotation containers list. Append this new
ruby segment at the end of ruby segments.
Let current bases be an empty list.
Let current bases range be null.
Let current bases range start be null.
Let current annotation containers be an empty list.
When the steps above say to commit the base range, it means to run the following
steps at that point in the algorithm:
If current bases is empty, abort these steps.
If current bases range is not null, abort these steps.
Let current bases range be a DOM range whose start is the boundary
point (root, current bases range start) and whose end is the boundary
point (root, index).
When the steps above say to commit current annotations, it means to run the
following steps at that point in the algorithm:
If current annotations is not empty and current annotations range is
null let current annotations range be a DOM range whose start is the boundary
point (root, current annotations range start) and whose end is the boundary
point (root, index).
If current annotations is not empty, create a new ruby annotation
container. It is described by an annotations list set to current
annotations and a range set to current annotations range. Append this new
ruby annotation container at the end of current annotation
containers.
Let current annotations be an empty list of DOM ranges.
Let current annotations range be null.
Let current annotations range start be null.
When the steps above say to commit an automatic base, it means to run the
following steps at that point in the algorithm:
If current automatic base nodes is empty, abort these steps.
If current automatic base nodes contains nodes that are not Text
nodes, or Text nodes that are not inter-element whitespace, then
run these substeps:
It current bases is empty, set current bases range start to the
value of current automatic base range start.
Create a new DOM range whose start is the
boundary point (root, current
automatic base range start) and whose end
is the boundary point (root,
index), and append it at the end of current bases.
Let current automatic base nodes be an empty list of DOM Nodes.
An rb element's end tag may be omitted
if the rb element is immediately followed by an rb, rt,
rtc or rp element, or if there is no more content in the parent
element.
The rb element marks the base text component of a ruby annotation. When it is
the child of a ruby element, it doesn't represent anything itself, but its parent ruby
element uses it as part of determining what itrepresents.
An rb element that is not a child of a ruby element
represents the same thing as its children.
An rt element's end tag may be omitted if the
rt element is immediately followed by an rb, rt, rtc or
rp element, or if there is no more content in the parent element.
The rt element marks the ruby text component of a ruby annotation. When it is
the child of a ruby element or of an rtc element that is itself
the child of a ruby element, it doesn't represent anything itself, but its ancestor ruby
element uses it as part of determining what itrepresents.
An rt element that is not a child of a ruby element or of an
rtc element that is itself the child of a ruby element
represents the same thing as its children.
An rtc element's end tag may be omitted
if the rtc element is immediately followed by an rb,
rtc or rp element, or if there is no more content in the parent
element.
The rtc element marks a ruby text container for ruby text components
in a ruby annotation. When it is the child of a ruby element it doesn't represent anything itself, but its parent ruby element
uses it as part of determining what itrepresents.
An rtc element that is not a child of a ruby element
represents the same thing as its children.
When an rtc element is processed as part of the segmentation and
categorisation of content for a ruby element, the following algorithm
defines how to process an rtc element:
Let root be the rtc element for which the algorithm is
being run.
Let index be 0.
Let annotations be an empty list of DOM ranges.
Let current automatic annotation nodes be an empty list of DOM nodes.
Let current automatic annotation range start be null.
Process an rtc child: If index is equal to or greater than the number of
child nodes in root, then run the steps to commit an automatic
annotation, return annotations, and abort these steps.
Let current child be the indexth node in root.
If current child is an rt element, then run these substeps:
Create a new DOM range whose start is the
boundary point (root,
index) and whose end is the boundary point (root, index plus
one), and append it at the end of annotations.
Increment index by one and jump to the step labelled process an rtc
child.
If current automatic annotation nodes is empty, set current automatic
annotation range start to the value of index.
Append current child at the end of current automatic annotation
nodes.
Increment index by one and jump to the step labelled process an rtc
child.
When the steps above say to commit an automatic annotation, it means to run the
following steps at that point in the algorithm:
If current automatic annotation nodes is empty, abort these steps.
If current automatic annotation nodes contains nodes that are not
Text nodes, or Text nodes that are not inter-element
whitespace, then create a new DOM range whose start is the boundary
point (root, current automatic annotation range start) and
whose end is the boundary point (root, index), and
append it at the end of annotations.
Let current automatic annotation nodes be an empty list of DOM nodes.
Let current automatic annotation range start be null.
An rp element's end tag may be omitted
if the rp element is immediately followed by an rb, rt,
rtc or rp element, or if there is no more content in the parent
element.
The rp element is used to provide fallback text to be shown by user agents that
don't support ruby annotations. One widespread convention is to provide parentheses around
the ruby text component of a ruby annotation.
The contents of the rp elements are typically not displayed by user agents
which do support ruby annotations
An rp element that is a child of a ruby
elementrepresents nothing. An rp
element whose parent element is not a ruby element represents its
children.
The example shown previously, in which each ideograph in the text 漢字 is annotated with its phonetic reading, could be expanded
to use rp so that in legacy user agents the readings are in parentheses (please
note that white space has been introduced into this example in order to make it more
readable):
...
漢
字
...
In conforming user agents the rendering would be as above, but in user agents that do not
support ruby, the rendering would be:
... 漢字 (かんじ) ...
When there are multiple annotations for a segment, rp elements can also be
placed between the annotations. Here is another copy of an earlier contrived example showing
some symbols with names given in English and French using double-sided annotations, but this
time with rp elements as well:
♥
☘
✶
This would make the example render as follows in non-ruby-capable user agents:
This element is especially useful when embedding user-generated content with an unknown
directionality.
In this example, usernames are shown along with the number of posts that the user has
submitted. If the bdi element were not used, the username of the Arabic user would
end up confusing the text (the bidirectional algorithm would put the colon and the number "3"
next to the word "User" rather than next to the word "posts").
The bdo element represents explicit text directionality formatting
control for its children. It allows authors to override the Unicode bidirectional algorithm by
explicitly specifying a direction override. [BIDI]
Authors must specify the dir attribute on this element, with the
value ltr to specify a left-to-right override and with the value rtl to
specify a right-to-left override. The auto value must not be specified.
In this example, a code fragment is marked up using
span elements and class attributes so that its keywords and
identifiers can be color-coded from CSS:
While line breaks are usually represented in visual media by physically moving
subsequent text to a new line, a style sheet or user agent would be equally justified in causing
line breaks to be rendered in a different manner, for instance as green dots, or as extra
spacing.
br elements must be used only for line breaks that are actually part of the
content, as in poems or addresses.
The following example is correct usage of the br element:
P. Sherman
42 Wallaby Way
Sydney
br elements must not be used for separating thematic groups in a paragraph.
The following examples are non-conforming, as they abuse the br element:
If a paragraph consists of nothing but a single br element, it
represents a placeholder blank line (e.g. as in a template). Such blank lines must not be used for
presentation purposes.
Any content inside br elements must not be considered part of the surrounding
text.
The wbr element represents a line break opportunity.
In the following example, someone is quoted as saying something which, for effect, is written
as one long word. However, to ensure that the text can be wrapped in a readable fashion, the
individual words in the quote are separated using a wbr element.
So then he pointed at the tiger and screamed
"thereisnowayyouareevergoingtocatchme"!
Here, especially long lines of code in a program listing have suggested wrapping points given
using wbr elements.
