One of the strengths of open access materials is the ability to improve a work’s accessibility or building a work with accessibility and usability in mind. Accessibility means someone with a disability must be able to obtain information as fully, equally, and independently as a person without a disability. User groups with special needs and disabilities can include blind users who use screen reader software, low vision and/or colorblind users, users with low technology access or skill levels, and low-mobility users who use only keyboard controls. 

Web Content Accessibility Guidelines (WCAG) have become the standard for digital accessibility. WCAG provides guidelines and success criteria revolve around four basic principles:  

•     Perceivability is concerned with whether information is consumable and visible to all users. Information should be displayed in different ways, such as providing text transcripts for audio or alt text for images.
•     Operability applies to whether users can effectively operate and navigate a website with a variety of tools. For example, providing proper headings or descriptive linking would help make webpages more compatible with screen readers and voice recognition software.
•     Understandable is concerned with whether operations and information are clear and concise. So here, descriptive instructions and unambiguous error messages would help make a page more understandable to users needing to complete a specified task.
•     Robust when they can be used with a multitude of browsers, devices, and assistive technologies.

At a minimum, you and co-authors need to carefully consider accessible software and file formats, image and text readability, provide alternative text and captions, use descriptive link text, and use accessible fonts and colors. Much of this information is available on WashU’s Digital Accessibility Guide and web accessibility best practices. 

The CUNY Office of Library Services has additional resources and content for creating accessible open educational resources (OER) specifically, and there's also a checklist from BCampus.

Additional terminology and tools regarding accessibility is available in the Library Accessibility Toolkit.

See Johnathan Poritz's Adaptation Status Chart that explains how the status of the original work influences the status of the adaptation, as well as influencing in an unexpected way the possible uses of the adaptation.

Poritz's Remix Compatibility Chart and Allowed Remix Status Chart is a helpful tool when making a remix of two works--a new work with sufficient creativity to warrant its own independent copyright, but which is also simultaneously a derivative of two other works.

Please see our guide Tools for searching and choosing openly licensed books for courses and our Guide to OER.