<dt> and <dd> elements must be contained by a <dl>

Rule Description

Definition list items (<dt> and/or <dd>) must be wrapped in parent <dl> elements to be valid. This enables screen reader users to understand the proper hierarchy of information in the list.

The Algorithm, in Simple Terms

Ensures that all child <dd> and <dt> elements have a <dl> as a parent.

Why this is Important

A definition list item must be wrapped in parent <dl> elements, otherwise it will be invalid.

A definition list must follow a specific hierarchy. A list is defined using the <dl> element. What follows are alternating sets of <dt> and <dd> elements, starting with the <dt> element. <dt> elements define a term while <dd> elements denote a term's description. Each set of <dt> elements must have a corresponding set of <dd> elements. Only <dt> and <dd> elements are allowed in definition list. If this hierarchy is not followed, the list will be invalid.

Compliance Data & Impact

User Impact: Serious
Disabilities Affected:
  • Blindness
  • Deafblindness
  • Mobility/Dexterity
Severity: Serious
Issue Type:
  • WCAG 2.0 (A): MUST
  • WCAG 2.1 (A): MUST
WCAG Success Criteria:
  • 1.3.1 Info and Relationships
Section 508 Guidelines:
  • Not applicable

How to Fix the Problem

Wrap the list item in parent <dl> elements to ensure the list follows the proper hierarchy. Furthermore, make sure that the <dt> and <dd> elements are in the proper order.

This rule checks for the valid hierarchical use of definition list elements to help screen reader users know what they are listening to, and what to expect as they listen to definition lists with regard to the organizational relationship of parent and child items.

For example, if you have the following code causing an error:

    <dd>Black hot drink</dd>
    <dd>White cold drink</dd>

Wrap it in the <dl> element:

        <dd>Black hot drink</dd>
        <dd>White cold drink</dd>

Related Deque University Course Pages

Other Related Resources

Additional Information

Relevant Technologies:
  • HTML 4
  • HTML5
Test Reliability: Automated testing is possible, with high accuracy
Rule ID: dlitem