1.3.2 Meaningful Sequence: When the sequence in which content is presented affects its meaning, a correct reading sequence can be programmatically determined.
SC 1.3.2 Meaningful Sequence supports the accessibility principle of Perceivable because people who are without vision or who have limited vision rely on AT, such as screen readers, to read content aloud, and they need to be able to access the information being presented in an order that makes sense. Users with limited vision may also use alternate style sheets to change fonts or increase font sizes, or to use color schemes that make it easier for them to read Web content.
The intent of SC 1.3.2 Meaningful Sequence is to ensure that, if the reading order is important to the understanding of the content, the AT is able to determine at least one reading order of the content that makes sense (also known as a “meaningful sequence”). Content that does not meet this SC may confuse or disorient AT users when the AT reads the content in the wrong order. However, if there is more than one meaningful sequence that preserves the meaning of the content, only one correct order needs to be provided.
In some cases, the order of the content does not matter. For example, a Web page may contain two independent articles. In this case, it does not matter which article is read first; there is no “meaningful sequence.” In this case, it does not matter which article is read first by the AT to the user.
In summary, if reading order is important for understanding the content, the developer of the Web page should make sure that the order of content in the underlying code is in the correct sequence no matter which technique is used to position and format the content or whether style sheets are in use.
Impact of Nonconformance with SC 1.3.2 Meaningful Sequence
| Type of Disability | Description of Impact |
|---|---|
| 302.1 Without Vision | Users who are blind cannot use a mouse to interact with electronic content and typically use an assistive technology, such as a screen reader, to get audible or other alternative output for the information represented visually. To be able to navigate the content, understand its structure and relationships, and understand the meaning of content represented in graphics and images, the content must provide textual and programmatic cues in addition to the content presented purely visually. |
| 302.2 With Limited Vision | Users with limited vision may have widely different visual perception. Individuals with limited vision may or may not use assistive technologies. Therefore, in addition to textual and programmatic cues necessary for assistive technologies, ICT must also present content consistently and predictably. Users who view content with magnifiers may not pick up alerts, warnings, or other content if such content is presented outside of a consistent and predictable navigation pattern or if the content is not itself viewable at large magnification. Content that becomes distorted when magnified can also prevent some users with limited vision from being able to understand or interact with the content. |
Applicability of Success Criteria 1.3.2 Meaningful Sequence
| Technology | Applicability of SC 1.3.2 |
|---|---|
| Web | Applies directly; source code order, applied styles, and properties such as tabindex, can all affect the order in which a user will encounter Web content. |
| Software | Applies directly; much like with Web content, native software developers can use code sequence, parent-child relationships, and tab order properties to affect the order in which a user encounters software content. |
| Office documents | Applies directly; in Office documents, users will typically encounter text in the same logical reading order it is presented. Other content, such as images, or other content inserted into the document rely on object anchors and text wrapping properties to determine their location and sequence in relation to other content. |
| PDF documents | Applies directly; in some PDF editing tools, content authors can directly define sequence for all content in a document. |
| Mobile Native | Applies directly; Mobile-native software developers can use code sequence, parent-child relationships, and tab order properties to affect the order in which a user encounters software content. |