Keyboard Navigation and Focus
General iframe accessibility guidelines apply. A user should be able to “tab” to the iframe and interact via the keyboard with its content. A user should be able to perceive that the iframe has focus. A user should be able to “tab” out of the embedded content and access the rest of the page.
Keybindings and other events bound to the parent
For the most part, interaction between the parent and content within an iframe are separated. This means that events bound to one are not transmitted to the other. If there are keyboard shortcuts bound to the parent, these will not be accessible from the child. For example, a shortcut to save bound in the parent will not be enacted on while focus is within the iframe.
Accessibility of the embedded content itself
It is important to be aware of the accessibility of the embedded content itself. The parent page may be highly accessible, but if the content held within the iframe is not, the user may not be able to complete their tasks and have a poor experience. For example, if something within the content of the iframe traps the keyboard and consumes all of its events, the user may not be able to navigate away from it and interact with any of the other elements on the parent page.
It is also useful to provide alternative content. For example a video, audio file, text, static image and etc.