Similar to the way that the epub:type attribute
adds semantics to elements, the WAI-ARIA role attribute can be used to inform assistive
technologies about the function a custom control serves (e.g., to indicate that an image functions like a
button). The list of supported roles for custom controls follows:
Defining the type of a control using the role attribute is only the first step. The state of
the control, and any properties associated with it, must also be maintained to ensure the reader can
correctly interact with the control:
States tell you something about the nature of the control: whether it is currently checked or not,
whether it is hidden, etc. These must be maintained as the reader interacts with the control,
otherwise they may get locked out of functionality (e.g., unable to reduce the volume, unable to make
important content visible, etc.).
Properties are typically set once and identify meta information such as the label or description for
a control (or element).