Techniques for WCAG 2.0

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# H40: Using definition lists

## Applicability

HTML and XHTML

This technique relates to:

- Success Criterion 3.1.3 (Unusual Words)
  - How to Meet 3.1.3 (Unusual Words)
  - Understanding Success Criterion 3.1.3 (Unusual Words)

## Description

The objective of this technique is to provide the definitions of words or phrases by presenting them in a definition list. The list is marked up using the `dl` element. Within the list, each term is put in a separate `dt` element, and its definition goes in the `dd` element directly following it. The `title` attribute can be used to provide additional information about the definition list.

Using `dl`, `dt`, and `dd` ensures that relationships between terms and their definitions are preserved if the presentation format changes and that the list of terms and definitions is treated as a unit.

Definition lists are easiest to use when the definitions are put in alphabetical order. Definition lists are typically used in a glossary.

## Examples

### Example 1

A list of definitions of nautical terms used on a Website about sailing.

Example Code:

    <dl title="Nautical terms">
      <dt>Knot</dt>
      <dd>
        <p>A <em>knot</em> is a unit of speed equaling 1
          nautical mile per hour (1.15 miles per hour or 1.852
          kilometers per hour).</p>
      </dd>
      <dt>Port</dt>
      <dd>
        <p><em>Port</em> is the nautical term (used on
          boats and ships) that refers to the left side
          of a ship, as perceived by a person facing towards
          the bow (the front of the vessel).</p>
      </dd>
      <dt>Starboard</dt>
      <dd>
        <p><em>Starboard</em> is the nautical term (used
          on boats and ships) that refers to the right
          side of a vessel, as perceived by a person
          facing towards the bow (the front of the vessel).</p>
      </dd>
    </dl>

## Resources

Resources are for information purposes only, no endorsement implied.

- Definition lists: the DL, DT, and DD elements

## Related Techniques

- G62: Providing a glossary

## Tests

### Procedure

For any set of words and their definitions that have the appearance of a list:

1. Check that the list is contained within a `dl` element.

2. Check that each word defined in the list is contained within a `dt` element.

3. Check that the definition for each word appears in the `dd` element immediately following the word's `dt` element .

### Expected Results

- All checks above are true.

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