11. XHTML List Module

This section is normative.

As its name suggests, the List Module provides list-oriented elements. Specifically, the List Module supports the following elements and attributes:

This module also defines the content set List with the content model (dl | nl | ol | ul)+ and adds this set to the Flow content set of the Structural Module.

Implementation: RELAX NG

XHTML offers authors several mechanisms for specifying lists of information. Lists may contain:

• Unordered information.
• Ordered information.
• Navigation information.
• Definitions.

The previous list, for example, is an unordered list, created with the ul element:

<ul>
<li>Unordered information. </li>
<li>Ordered information. </li>
<li>Navigation information. </li>
<li>Definitions. </li>
</ul>

An ordered list, created using the ol element, contains information where order is important, as in a recipe:

1. Mix dry ingredients thoroughly.
2. Pour in wet ingredients.
3. Mix for 10 minutes.
4. Bake for one hour at 300 degrees.

Definition lists, created using the dl element, generally consist of a series of term/definition pairs (although definition lists may have other applications). Thus, when advertising a product, one might use a definition list:

Lower cost

The new version of this product costs significantly less than the previous one!

Easier to use

We've changed the product so that it's much easier to use!

Safe for kids

You can leave your kids alone in a room with this product and they won't get hurt (not a guarantee).

defined in XHTML as:

<dl>
<dt>Lower cost</dt>
<dd>The new version of this product costs significantly less than the
previous one!</dd>
<dt>Easier to use</dt>
<dd>We've changed the product so that it's much easier to
use!</dd>
<dt>Safe for kids</dt>
<dd>You can leave your kids alone in a room with this product and
they won't get hurt (not a guarantee).</dd>
</dl>

11.1. Definition lists: the dl , di , dt , and dd elements

Definition lists vary only slightly from other types of lists in that list items consist of two parts: a term and a description. The term is given by the dt element. The description is given with a dd element. The term and its definition can be grouped within a di element to help clarify the relationship between a term and its definition(s).

<dl>
  <di>
    <dt>Dweeb</dt>
    <dd>young excitable person who may mature
      into a <em>Nerd</em> or <em>Geek</em></dd>
  </di>

  <di>
    <dt>Hacker</dt>
    <dd>a clever programmer</dd>
  </di>

  <di>
    <dt>Nerd</dt>
    <dd>technically bright but socially inept person</dd>
  </di>

</dl>

Here is an example with multiple terms and descriptions:

<dl>
   <dt>Center</dt>
   <dt>Centre</dt>
   <dd> A point equidistant from all points
              on the surface of a sphere.</dd>
   <dd> In some field sports, the player who
              holds the middle position on the field, court,
              or forward line.</dd>
</dl>

11.2. The nl element

Navigation lists are intended to be used to define lists of selectable items for ordered presentation. These may be presented in a number of ways, for instance as a navigation bar, or as a menu. Note that a navigation list always starts with a label element that defines the label for the list.

<nl>
   <label>Contents </label>
   <li href="#introduction">Introduction</li>
   <li>
      <nl>
          <label>Terms</label>
          <li href="#may">May</li>
          <li href="#must">Must</li>
          <li href="#should">Should</li>
      </nl>
   </li>
   <li href="#conformance">Conformance</li>
   <li href="#references">References</li>
   ...
</nl>

11.3. The ol and ul elements

Both types of lists are made up of sequences of list items defined by the li element. The difference is that ol lists represent lists of items that are essentially ordered (such as the steps of a recipe), while ul lists represent lists of items that are essentially unordered (such as shopping lists).

<ol>
   <li>Spring</li>
   <li>Summer</li>
   <li>Autumn</li>
   <li>Winter</li>
</ol>

11.4. The li element

The li element defines a list item within an ordered, unordered, or navigation list.

Within a list, each li element has an associated number, which is used for numbering list items in ordered lists:

• If the li element has a value attribute, the associated number is the value of that attribute;
• otherwise, if the li element is the first in the list, then the number has the value 1;
• otherwise the number is one higher than the number of the preceding li in the same list.

11.5. The label element

The label element is used to define a label for a list. The contents of the label element represent the title of a list (or sublist).

11.6. Issues