1. 4.14 Common idioms without dedicated elements
      1. 4.14.1 The main part of the content
      2. 4.14.2 Bread crumb navigation
      3. 4.14.3 Tag clouds
      4. 4.14.4 Conversations
      5. 4.14.5 Footnotes
    2. 4.15 Disabled elements
    3. 4.16 Matching HTML elements using selectors and CSS
      1. 4.16.1 Case-sensitivity of the CSS 'attr()' function
      2. 4.16.2 Case-sensitivity of selectors
      3. 4.16.3 Pseudo-classes

4.14 Common idioms without dedicated elements

4.14.1 The main part of the content

The main content of a page — not including headers and footers, navigation links, sidebars, advertisements, and so forth — can be marked up in a variety of ways, depending on the needs of the author.

The simplest solution is to not mark up the main content at all, and just leave it as implicit. Another way to think of this is that the body elements marks up the main content of the page, and the bits that aren't main content are excluded through the use of more appropriate elements like aside and nav.

Here is a short Web page marked up along this minimalistic school of thought. The main content is highlighted. Notice how all the other content in the body is marked up with elements to indicate that it's not part of the main content, in this case header, nav, and footer.

<!DOCTYPE HTML>
<html lang="en">
 <head>
  <title> My Toys </title>
 </head>
 <body>
  <header>
   <h1>My toys</h1>
  </header>
  <nav>
   <p><a href="/">Home</a></p>
   <p><a href="/contact">Contact</a></p>
  </nav>
  <p>I really like my chained book and my telephone. I'm not such a
  fan of my big ball.</p>
  <p>Another toy I like is my mirror.</p>
  <footer>
   <p>© copyright 2010 by the boy</p>
  </footer>
 </body>
</html>

If the main content is an independent unit of content that one could imagine syndicating independently, then the article element would be appropriate to mark up the main content of the document.

The document in the previous example is here recast as a blog post:

<!DOCTYPE HTML>
<html lang="en">
 <head>
  <title> The Boy Blog: My Toys </title>
 </head>
 <body>
  <header>
   <h1>The Boy Blog</h1>
  </header>
  <nav>
   <p><a href="/">Home</a></p>
   <p><a href="/contact">Contact</a></p>
  </nav>
  <article>
   <header>
    <h1>My toys</h1>
    <p>Published August 4th</p>
   </header>
   <p>I really like my chained book and my telephone. I'm not such a
   fan of my big ball.</p>
   <p>Another toy I like is my mirror.</p>
  </article>
  <footer>
   <p>© copyright 2010 by the boy</p>
  </footer>
 </body>
</html>

If the main content is not an independent unit of content so much as a section of a larger work, for instance a chapter, then the section element would be appropriate to mark up the main content of the document.

Here is the same document, but as a chapter in an online book:

<!DOCTYPE HTML>
<html lang="en">
 <head>
  <title> Chapter 2: My Toys — The Book of the Boy </title>
 </head>
 <body>
  <header>
   <hgroup>
    <h1>The Book of the Boy</h1>
    <h2>A book about boy stuff</h2>
   </hgroup>
  </header>
  <nav>
   <p><a href="/">Front Page</a></p>
   <p><a href="/toc">Table of Contents</a></p>
   <p><a href="/c1">Chapter 1</a> — <a href="/c3">Chapter 3</a></p>
  </nav>
  <section>
   <h1>Chapter 2: My Toys</h1>
   <p>I really like my chained book and my telephone. I'm not such a
   fan of my big ball.</p>
   <p>Another toy I like is my mirror.</p>
  </section>
 </body>
</html>

If neither article nor section would be appropriate, but the main content still needs an explicit element, for example for styling purposes, then the main element can be used.

This is the same as the original example, but using main for the main content instead of leaving it implied:

<!DOCTYPE HTML>
<html lang="en">
 <head>
  <title> My Toys </title>
  <style>
   body > main { background: navy; color: yellow; }
  </style>
 </head>
 <body>
  <header>
   <h1>My toys</h1>
  </header>
  <nav>
   <p><a href="/">Home</a></p>
   <p><a href="/contact">Contact</a></p>
  </nav>
  <main>
   <p>I really like my chained book and my telephone. I'm not such a
   fan of my big ball.</p>
   <p>Another toy I like is my mirror.</p>
  </main>
  <footer>
   <p>© copyright 2010 by the boy</p>
  </footer>
 </body>
</html>

4.14.2 Bread crumb navigation

This specification does not provide a machine-readable way of describing bread-crumb navigation menus. Authors are encouraged to just use a series of links in a paragraph. The nav element can be used to mark the section containing these paragraphs as being navigation blocks.

In the following example, the current page can be reached via two paths.

<nav>
 <p>
  <a href="/">Main</a> ▸
  <a href="/products/">Products</a> ▸
  <a href="/products/dishwashers/">Dishwashers</a> ▸
  <a>Second hand</a>
 </p>
 <p>
  <a href="/">Main</a> ▸
  <a href="/second-hand/">Second hand</a> ▸
  <a>Dishwashers</a>
 </p>
</nav>

4.14.3 Tag clouds

This specification does not define any markup specifically for marking up lists of keywords that apply to a group of pages (also known as tag clouds). In general, authors are encouraged to either mark up such lists using ul elements with explicit inline counts that are then hidden and turned into a presentational effect using a style sheet, or to use SVG.

Here, three tags are included in a short tag cloud:

<style>
.tag-cloud > li > span { display: none; }
.tag-cloud > li { display: inline; }
.tag-cloud-1 { font-size: 0.7em; }
.tag-cloud-2 { font-size: 0.9em; }
.tag-cloud-3 { font-size: 1.1em; }
.tag-cloud-4 { font-size: 1.3em; }
.tag-cloud-5 { font-size: 1.5em; }

@media speech {
  .tag-cloud > li > span { display:inline }
}
</style>
...
<ul class="tag-cloud">
 <li class="tag-cloud-4"><a title="28 instances" href="/t/apple">apple</a> <span>(popular)</span>
 <li class="tag-cloud-2"><a title="6 instances"  href="/t/kiwi">kiwi</a> <span>(rare)</span>
 <li class="tag-cloud-5"><a title="41 instances" href="/t/pear">pear</a> <span>(very popular)</span>
</ul>

The actual frequency of each tag is given using the title attribute. A CSS style sheet is provided to convert the markup into a cloud of differently-sized words, but for user agents that do not support CSS or are not visual, the markup contains annotations like "(popular)" or "(rare)" to categorize the various tags by frequency, thus enabling all users to benefit from the information.

The ul element is used (rather than ol) because the order is not particularly important: while the list is in fact ordered alphabetically, it would convey the same information if ordered by, say, the length of the tag.

The tag rel-keyword is not used on these a elements because they do not represent tags that apply to the page itself; they are just part of an index listing the tags themselves.

4.14.4 Conversations

This specification does not define a specific element for marking up conversations, meeting minutes, chat transcripts, dialogues in screenplays, instant message logs, and other situations where different players take turns in discourse.

Instead, authors are encouraged to mark up conversations using p elements and punctuation. Authors who need to mark the speaker for styling purposes are encouraged to use span or b. Paragraphs with their text wrapped in the i element can be used for marking up stage directions.

This example demonstrates this using an extract from Abbot and Costello's famous sketch, Who's on first:

<p> Costello: Look, you gotta first baseman?
<p> Abbott: Certainly.
<p> Costello: Who's playing first?
<p> Abbott: That's right.
<p> Costello becomes exasperated.
<p> Costello: When you pay off the first baseman every month, who gets the money?
<p> Abbott: Every dollar of it.

The following extract shows how an IM conversation log could be marked up, using the data element to provide Unix timestamps for each line. Note that the timestamps are provided in a format that the time element does not support, so the data element is used instead (namely, Unix time_t timestamps). Had the author wished to mark up the data using one of the date and time formats supported by the time element, that element could have been used instead of data. This could be advantageous as it would allow data analysis tools to detect the timestamps unambiguously, without coordination with the page author.

<p> <data value="1319898155">14:22</data> <b>egof</b> I'm not that nerdy, I've only seen 30% of the star trek episodes
<p> <data value="1319898192">14:23</data> <b>kaj</b> if you know what percentage of the star trek episodes you have seen, you are inarguably nerdy
<p> <data value="1319898200">14:23</data> <b>egof</b> it's unarguably
<p> <data value="1319898228">14:23</data> <i>* kaj blinks</i>
<p> <data value="1319898260">14:24</data> <b>kaj</b> you are not helping your case

HTML does not have a good way to mark up graphs, so descriptions of interactive conversations from games are more difficult to mark up. This example shows one possible convention using dl elements to list the possible responses at each point in the conversation. Another option to consider is describing the conversation in the form of a DOT file, and outputting the result as an SVG image to place in the document. [DOT]

<p> Next, you meet a fisher. You can say one of several greetings:
<dl>
 <dt> "Hello there!"
 <dd>
  <p> She responds with "Hello, how may I help you?"; you can respond with:
  <dl>
   <dt> "I would like to buy a fish."
   <dd> <p> She sells you a fish and the conversation finishes.
   <dt> "Can I borrow your boat?"
   <dd>
    <p> She is surprised and asks "What are you offering in return?".
    <dl>
     <dt> "Five gold." (if you have enough)
     <dt> "Ten gold." (if you have enough)
     <dt> "Fifteen gold." (if you have enough)
     <dd> <p> She lends you her boat. The conversation ends.
     <dt> "A fish." (if you have one)
     <dt> "A newspaper." (if you have one)
     <dt> "A pebble." (if you have one)
     <dd> <p> "No thanks", she replies. Your conversation options
     at this point are the same as they were after asking to borrow
     her boat, minus any options you've suggested before.
    </dl>
   </dd>
  </dl>
 </dd>
 <dt> "Vote for me in the next election!"
 <dd> <p> She turns away. The conversation finishes.
 <dt> "Madam, are you aware that your fish are running away?"
 <dd>
  <p> She looks at you skeptically and says "Fish cannot run, miss".
  <dl>
   <dt> "You got me!"
   <dd> <p> The fisher sighs and the conversation ends.
   <dt> "Only kidding."
   <dd> <p> "Good one!" she retorts. Your conversation options at this
   point are the same as those following "Hello there!" above.
   <dt> "Oh, then what are they doing?"
   <dd> <p> She looks at her fish, giving you an opportunity to steal
   her boat, which you do. The conversation ends.
  </dl>
 </dd>
</dl>

In some games, conversations are simpler: each character merely has a fixed set of lines that they say. In this example, a game FAQ/walkthrough lists some of the known possible responses for each character:

<section>
 <h1>Dialogue</h1>
 <p><small>Some characters repeat their lines in order each time you interact
 with them, others randomly pick from amongst their lines. Those who respond in
 order have numbered entries in the lists below.</small>
 <h2>The Shopkeeper</h2>
 <ul>
  <li>How may I help you?
  <li>Fresh apples!
  <li>A loaf of bread for madam?
 </ul>
 <h2>The pilot</h2>
 <p>Before the accident:
 <ul>
  <li>I'm about to fly out, sorry!
  <li>Sorry, I'm just waiting for flight clearance and then I'll be off!
 </ul>
 <p>After the accident:
 <ol>
  <li>I'm about to fly out, sorry!
  <li>Ok, I'm not leaving right now, my plane is being cleaned.
  <li>Ok, it's not being cleaned, it needs a minor repair first.
  <li>Ok, ok, stop bothering me! Truth is, I had a crash.
 </ol>
 <h2>Clan Leader</h2>
 <p>During the first clan meeting:
 <ul>
  <li>Hey, have you seen my daughter? I bet she's up to something nefarious again...
  <li>Nice weather we're having today, eh?
  <li>The name is Bailey, Jeff Bailey. How can I help you today?
  <li>A glass of water? Fresh from the well!
 </ul>
 <p>After the earthquake:
 <ol>
  <li>Everyone is safe in the shelter, we just have to put out the fire!
  <li>I'll go and tell the fire brigade, you keep hosing it down!
 </ol>
</section>

4.14.5 Footnotes

HTML does not have a dedicated mechanism for marking up footnotes. Here are the suggested alternatives.

For short inline annotations, the title attribute could be used.

In this example, two parts of a dialogue are annotated with footnote-like content using the title attribute.

<p> <b>Customer</b>: Hello! I wish to register a complaint. Hello. Miss?
<p> <b>Shopkeeper</b>: <span title="Colloquial pronunciation of 'What do you'"
>Watcha</span> mean, miss?
<p> <b>Customer</b>: Uh, I'm sorry, I have a cold. I wish to make a complaint.
<p> <b>Shopkeeper</b>: Sorry, <span title="This is, of course, a lie.">we're
closing for lunch</span>.

Unfortunately, relying on the title attribute is currently discouraged as many user agents do not expose the attribute in an accessible manner as required by this specification (e.g. requiring a pointing device such as a mouse to cause a tooltip to appear, which excludes keyboard-only users and touch-only users, such as anyone with a modern phone or tablet).

If the title attribute is used, CSS can be used to draw the reader's attention to the elements with the attribute.

For example, the following CSS places a dashed line below elements that have a title attribute.

[title] { border-bottom: thin dashed; }

For longer annotations, the a element should be used, pointing to an element later in the document. The convention is that the contents of the link be a number in square brackets.

In this example, a footnote in the dialogue links to a paragraph below the dialogue. The paragraph then reciprocally links back to the dialogue, allowing the user to return to the location of the footnote.

<p> Announcer: Number 16: The <i>hand</i>.
<p> Interviewer: Good evening. I have with me in the studio tonight
Mr Norman St John Polevaulter, who for the past few years has been
contradicting people. Mr Polevaulter, why <em>do</em> you
contradict people?
<p> Norman: I don't. <sup><a href="#fn1" id="r1">[1]</a></sup>
<p> Interviewer: You told me you did!
...
<section>
 <p id="fn1"><a href="#r1">[1]</a> This is, naturally, a lie,
 but paradoxically if it were true he could not say so without
 contradicting the interviewer and thus making it false.</p>
</section>

For side notes, longer annotations that apply to entire sections of the text rather than just specific words or sentences, the aside element should be used.

In this example, a sidebar is given after a dialogue, giving it some context.

<p> <span class="speaker">Customer</span>: I will not buy this record, it is scratched.
<p> <span class="speaker">Shopkeeper</span>: I'm sorry?
<p> <span class="speaker">Customer</span>: I will not buy this record, it is scratched.
<p> <span class="speaker">Shopkeeper</span>: No no no, this's'a tobacconist's.
<aside>
 <p>In 1970, the British Empire lay in ruins, and foreign
 nationalists frequented the streets — many of them Hungarians
 (not the streets — the foreign nationals). Sadly, Alexander
 Yalt has been publishing incompetently-written phrase books.
</aside>

For figures or tables, footnotes can be included in the relevant figcaption or caption element, or in surrounding prose.

In this example, a table has cells with footnotes that are given in prose. A figure element is used to give a single legend to the combination of the table and its footnotes.

<figure>
 <figcaption>Table 1. Alternative activities for knights.</figcaption>
 <table>
  <tr>
   <th> Activity
   <th> Location
   <th> Cost
  <tr>
   <td> Dance
   <td> Wherever possible
   <td> £0<sup><a href="#fn1">1</a></sup>
  <tr>
   <td> Routines, chorus scenes<sup><a href="#fn2">2</a></sup>
   <td> Undisclosed
   <td> Undisclosed
  <tr>
   <td> Dining<sup><a href="#fn3">3</a></sup>
   <td> Camelot
   <td> Cost of ham, jam, and spam<sup><a href="#fn4">4</a></sup>
 </table>
 <p id="fn1">1. Assumed.</p>
 <p id="fn2">2. Footwork impeccable.</p>
 <p id="fn3">3. Quality described as "well".</p>
 <p id="fn4">4. A lot.</p>
</figure>

4.15 Disabled elements

An element is said to be actually disabled if it is one of the following:

This definition is used to determine what elements can be focused and which elements match the :enabled and :disabled pseudo-classes.

4.16 Matching HTML elements using selectors and CSS

4.16.1 Case-sensitivity of the CSS 'attr()' function

The CSS Values and Units specification leaves the case-sensitivity of attribute names for the purpose of the 'attr()' function to be defined by the host language. [CSSVALUES]

When comparing the attribute name part of a CSS 'attr()' function to the names of namespace-less attributes on HTML elements in HTML documents, the name part of the CSS 'attr()' function must first be converted to ASCII lowercase. The same function when compared to other attributes must be compared according to its original case. In both cases, the comparison is case-sensitive.

This is the same as comparing the name part of a CSS attribute selector, specified in the next section.

4.16.2 Case-sensitivity of selectors

The Selectors specification leaves the case-sensitivity of element names, attribute names, and attribute values to be defined by the host language. [SELECTORS]

When comparing a CSS element type selector to the names of HTML elements in HTML documents, the CSS element type selector must first be converted to ASCII lowercase. The same selector when compared to other elements must be compared according to its original case. In both cases, the comparison is case-sensitive.

When comparing the name part of a CSS attribute selector to the names of attributes on HTML elements in HTML documents, the name part of the CSS attribute selector must first be converted to ASCII lowercase. The same selector when compared to other attributes must be compared according to its original case. In both cases, the comparison is case-sensitive.

Attribute selectors on an HTML element in an HTML document must treat the values of attributes with the following names as ASCII case-insensitive, with one exception as noted in the rendering section:

For example, the selector [bgcolor="#ffffff"] will match any HTML element with a bgcolor attribute with values including #ffffff, #FFFFFF and #fffFFF. This happens even if bgcolor has no effect for a given element (e.g., div).

All other attribute values and everything else must be treated as entirely case-sensitive for the purposes of selector matching. This includes:

Selectors defines that ID and class selectors (such as #foo and .bar), when matched against elements in documents that are in quirks mode, will be matched in an ASCII case-insensitive manner. However, this does not apply for attribute selectors with "id" or "class" as the name part. The selector [class="foobar"] will treat its value as case-sensitive even in quirks mode.

4.16.3 Pseudo-classes

There are a number of dynamic selectors that can be used with HTML. This section defines when these selectors match HTML elements. [SELECTORS] [CSSUI]

:defined

The :defined pseudo-class must match any element that is defined.

:link
:visited

All a elements that have an href attribute, all area elements that have an href attribute, and all link elements that have an href attribute, must match one of :link and :visited.

Other specifications might apply more specific rules regarding how these elements are to match these pseudo-classes, to mitigate some privacy concerns that apply with straightforward implementations of this requirement.

:active

The :active pseudo-class is defined to match an element while an element is being activated by the user.

To determine whether a particular element is being activated for the purposes of defining the :active pseudo-class only, an HTML user agent must use the first relevant entry in the following list.

If the element has a descendant that is currently matching the :active pseudo-class

The element is being activated.

If the element is the labeled control of a label element that is currently matching :active

The element is being activated.

If the element is a button element
If the element is an input element whose type attribute is in the Submit Button, Image Button, Reset Button, or Button state

The element is being activated if it is in a formal activation state and it is not disabled.

For example, if the user is using a keyboard to push a button element by pressing the space bar, the element would match this pseudo-class in between the time that the element received the keydown event and the time the element received the keyup event.

If the element is an a element that has an href attribute
If the element is an area element that has an href attribute
If the element is a link element that has an href attribute
If the element has its tabindex focus flag set

The element is being activated if it is in a formal activation state.

If the element is being actively pointed at

The element is being activated.

An element is said to be in a formal activation state between the time the user begins to indicate an intent to trigger the element's activation behavior and either the time the user stops indicating an intent to trigger the element's activation behavior, or the time the element's activation behavior has finished running, which ever comes first.

An element is said to be being actively pointed at while the user indicates the element using a pointing device while that pointing device is in the "down" state (e.g. for a mouse, between the time the mouse button is pressed and the time it is depressed; for a finger in a multitouch environment, while the finger is touching the display surface).

:hover

The :hover pseudo-class is defined to match an element while the user designates an element with a pointing device. For the purposes of defining the :hover pseudo-class only, an HTML user agent must consider an element as being one that the user designates if it is:

Consider in particular a fragment such as:

<p> <label for=c> <input id=a> </label> <span id=b> <input id=c> </span> </p>

If the user designates the element with ID "a" with their pointing device, then the p element (and all its ancestors not shown in the snippet above), the label element, the element with ID "a", and the element with ID "c" will match the :hover pseudo-class. The element with ID "a" matches it from condition 1, the label and p elements match it because of condition 2 (one of their descendants is designated), and the element with ID "c" matches it through condition 3 (its label element matches :hover). However, the element with ID "b" does not match :hover: its descendant is not designated, even though it matches :hover.

:focus

For the purposes of the CSS :focus pseudo-class, an element has the focus when its top-level browsing context has the system focus, it is not itself a browsing context container, and it is one of the elements listed in the focus chain of the currently focused area of the top-level browsing context.

:target

For the purposes of the CSS :target pseudo-class, the Document's target elements are a list containing the Document's target element, if it is not null, or containing no elements, if it is. [SELECTORS]

:enabled

The :enabled pseudo-class must match any button, input, select, textarea, optgroup, option, or fieldset element that is not actually disabled.

:disabled

The :disabled pseudo-class must match any element that is actually disabled.

:checked

The :checked pseudo-class must match any element falling into one of the following categories:

:indeterminate

The :indeterminate pseudo-class must match any element falling into one of the following categories:

:default

The :default pseudo-class must match any element falling into one of the following categories:

:placeholder-shown

The :placeholder-shown pseudo-class must match any element falling into one of the following categories:

:valid

The :valid pseudo-class must match any element falling into one of the following categories:

:invalid

The :invalid pseudo-class must match any element falling into one of the following categories:

:in-range

The :in-range pseudo-class must match all elements that are candidates for constraint validation, have range limitations, and that are neither suffering from an underflow nor suffering from an overflow.

:out-of-range

The :out-of-range pseudo-class must match all elements that are candidates for constraint validation, have range limitations, and that are either suffering from an underflow or suffering from an overflow.

:required

The :required pseudo-class must match any element falling into one of the following categories:

:optional

The :optional pseudo-class must match any element falling into one of the following categories:

:read-only
:read-write

The :read-write pseudo-class must match any element falling into one of the following categories, which for the purposes of Selectors are thus considered user-alterable: [SELECTORS]

The :read-only pseudo-class must match all other HTML elements.

:dir(ltr)

The :dir(ltr) pseudo-class must match all elements whose directionality is 'ltr'.

:dir(rtl)

The :dir(rtl) pseudo-class must match all elements whose directionality is 'rtl'.

This specification does not define when an element matches the :lang() dynamic pseudo-class, as it is defined in sufficient detail in a language-agnostic fashion in the Selectors specification. [SELECTORS]