This is a really short guideline this time. The guideline explains it is necessary to “ensure that the user interface follows principles of accessible design: device-independent access to functionality, keyboard operability, self-voicing, etc.” It also explains how if the embedded object has its “own interface”, the interface must be accessible. If the interface of the embedded object cannot be made accessible, an alternative accessible solution should be provided.
The following is the only checkpoint for this guideline.
Checkpoint 8.1 - Make programmatic elements such as scripts and applets directly accessible or compatible with assistive technologies
This checkpoint is so important that it was given a priority 1 status and must be implemented into every website that meets the criteria. It is extremely important to have the user be able to control their environment as much as possible. Without control of the environment and the ability to get necessary aids from the site, users are likely going to not visit this site often. To gain full details on this guideline follow this link.