...
Enable navigation through keyboard short-cuts
All the content types with html as base like ECML,QuML, PDF contents need to be accessible compliant.
Ex:
ECML : In Case of ECML, All the HTML tags generated should be accessible compliant. Questions,Answers should be added with ARIA labels, roles. Images has to be considered for alt text content embedded onto the image attribute.
PDF :
Enable assets have auto-readability for image etc.
...