The following is a list of several ways in which user agents are commonly involved in web content authoring and the relationship between UAAG 2.0 and ATAG 2.0.
1. Preview tool: Authors often preview their work in user agents to test how the content will be appear and operate. ATAG 2.0 includes a special exception when previews are implemented with pre-existing user agents, so there are no additional requirements on user agent developers in this case.
2. Checking tool: Authors often make use of user agent error panels (e.g. HTML validity, JavaScript errors) during authoring. ATAG 2.0 Part A applies, but may not include additional accessibility requirements beyond the UAAG 2.0 success criteria. If a user agent includes an "accessibility checker", the developer should consult checker implementation guidance in ATAG 2.0 Part B.
3. Edit modes: Some user agents include a mode where the user can edit and save changes to the web content, modifying the experience of other users. In this mode, the user agent is acting as an authoring tool and all of ATAG 2.0 applies.
4. Automatic content changes: Some user agents or plug-ins can automatically change retrieved web content before it's rendered. This functionality is not considered an authoring tool because changes are made to the user's own experience, not the experience of other users.
5. Providing a platform for web-based authoring tools: Many web applications serve as authoring tools and make use of user agent features to deliver functionality (e.g. undo text entry, adjust font size of the authoring tool user interface etc.). User agent developers should consult ATAG 2.0 to understand the ways in which web-based authoring tools can depend on user agent features.