Extended Descriptions Use Cases and Reading System Expectations

This document outlines use cases for extended descriptions in EPUB and web content, addressing the need for standardized semantic markup and consistent reading system behavior. Extended descriptions provide detailed textual alternatives for complex visual content including images, diagrams, tables, videos, and mathematical formulas. The standardization of extended descriptions is important for interoperability, and user experience consistency across the digital publishing ecosystem.

User Stories

Visual Reader

• As a student using visual materials I want to access detailed descriptions of complex diagrams and charts, so that I can fully understand the educational content
• As a visual reader I want to easily identify when images have extended descriptions available, so that I can access additional context and information when needed
• As a visual reader I want to access extended descriptions without losing my place in the content, so that I can return to my reading position efficiently

Screen Reader User

• As a screen reader user I want extended descriptions to be programmatically identifiable, so that my assistive technology can announce their availability
• As a screen reader user I want to easily access to extended descriptions, so that I can better understand the content without difficulties
• As a screen reader user I want to return to the exact location where I accessed an extended description, so that I maintain my reading flow and don't lose context

Audio/TTS User

• As a listener consuming content via TTS I want configurable verbosity settings for extended descriptions, so that I can choose the level of detail appropriate for my needs
• As a listener consuming content via TTS I want the ability to skip extended descriptions when needed, so that I can maintain listening flow when descriptions are not relevant

Publisher/Author

• As a content creator I want clear, standardized markup patterns for extended descriptions, so that I can ensure consistency and accessibility across my publications
• As a publisher I want to provide extended descriptions without disrupting visual design, so that I can maintain aesthetic quality while ensuring accessibility
• As a publisher I want to add extended description to a print-first book, so that I don't have to rearrange all the content
• As a content creator I want extended descriptions to work consistently across different reading systems, so that all users receive the same accessible experience

Web Content Creator

• As a web content creator I want extended description patterns that work in both EPUB and general web contexts, so that I can maintain consistency across different publication formats

Authoring Tool

• As a EPUB authoring tool developer I want to programmatically identify which images have extended descriptions, so that edit EPUB files with specific UI for managing extended descriptions
• As a authoring tool developer I want a standardized markup templates for extended descriptions, so that I can automate proper semantic tagging

Quality Assurance Tool

• As a quality assurance tool (like ACE) I want to systematically identify extended descriptions, so that I can provide accurate extended description reports
• As a content management system I want to generate inventories of all extended descriptions in a publication, so that publishers can track and maintain their accessible content

Reading System Developer

• As a reading system developer I want standardized semantic roles for extended description markup, so that I can implement consistent user interface behaviors
• As a reading system developer I want programmatically identifiable extended descriptions, so that I can develop innovative presentation methods (sidebars, overlays, detail views)

Reading System Expectations

• Programmatic Access: reading systems should ensure that extended descriptions are programmatically accessible to assistive technologies through standard APIs (accessibility tree, DOM, etc.).
• Programmatic Access: reading systems should provide keyboard-accessible methods to discover and access extended descriptions.
• Return Navigation: reading systems should provide a mechanism for users to return to their original reading position after accessing an extended description, particularly when the description is in a separate document or non-linear location.
• Return Navigation: reading systems should announce the availability of extended descriptions to TTS users and provide accessible methods to access them.