Be specific when including accessibility requirements in a project charter or as part of the business requirements for a procurement effort. Consider how a general statements such as "the product must be accessible," or "product must meet federal and state accessibility requirements" do not really help to clarify what must be done. The second statement is better, but it still would require familiarity with federal and state law to meet that objective. Instead, consider the following:
"The product must meet the Web Content Accessibility Guidelines (WCAG) 2.0 Level AA requirements as referenced in Section 508 of the Rehabilitation Act of 1973, as amended."
The above is specific, pointing to WCAG 2.0 Level AA requirements, which are easy to find with a web search, and ties this requirement to federal law. The WCAG 2.0 requirements are well documented, and there are many checklists available for easy reference.
This statement could have cited the Illinois Information Technology Accessibility Act (IITAA), instead of Section 508, as the state law has been harmonized with federal law: Conformance with one guarantees conformance with the other. That being said, if formulating requirements for a sole-source or competitive bid, vendors more readily accept references to federal law.
Note: WCAG 2.x requirements are called Success Criteria and are divided into three levels (A, AA, and AAA). Level AA contains all Level A requirements and is the level that is required by federal and state law. Do not use or require Level AAA Success Criteria, as Level AAA is intended for specific use cases, were there is an identified need that cannot be met by Level AA requirements. If a specific need would require Level AAA support, only utilize those Success Criteria that are applicable for the identified need.
If there are additional identified accessibility requirements, such as a specific need to support a given assistive technology, be sure to specify that requirement in addition to the accessibility standard to be met.