What is the role of long descriptions for complex images in DITA?

Long descriptions in DITA serve a critical role for complex images by providing detailed textual explanations that make the content accessible to individuals with disabilities and others who may not interpret the image’s meaning intuitively.

Complex images often include intricate details or convey specific information that may not be immediately evident to all readers. Long descriptions in DITA play a crucial role in ensuring accessibility and understanding for a diverse audience.


Long descriptions are primarily used to make images accessible to people with visual or cognitive disabilities. When an image is complex and cannot be fully understood through visual examination, a long description provides a textual alternative that conveys the image’s essential content.

Textual Detail

The long description should offer a detailed, comprehensive explanation of the image’s content. It may include information about the image’s components, relationships, spatial arrangements, and any other relevant details that are essential for understanding the image’s purpose.

Diverse Formats

In DITA, long descriptions are typically included as separate elements or attributes within the topic structure, allowing for flexibility in formatting and presentation. This flexibility is essential because long descriptions can be output in various formats, depending on user needs.

Compliance and Inclusivity

Long descriptions are crucial for organizations striving to comply with accessibility standards such as WCAG (Web Content Accessibility Guidelines). By providing long descriptions, organizations ensure that their documentation is inclusive and can be accessed by a wider audience.


A user manual for a complex piece of machinery in the manufacturing industry includes detailed schematics and diagrams of the machinery’s internal components, which are essential for troubleshooting. In the DITA content, complex images are tagged with a long description element.

For a schematic showing the hydraulic system, the long description will provide a textual breakdown of each component, their connections, and their functions. This ensures that readers, including those with visual impairments, can fully grasp the content and troubleshoot effectively. When the documentation is output in HTML format, the long descriptions are presented alongside or linked from the images, making the content accessible and understandable to a wide range of users.