PDF/UA is the ISO standard for accessible PDF technology. The PDF Association’s PDF/UA Competence Center has released an algorithm encompassing all “shall” statements in ISO 14289-1 (PDF/UA). This document, the Matterhorn Protocol, provides the definitive technical blueprint for accessible PDF files. There’s already an implementation of the Matterhorn Protocol in PAC 2.0, the free accessibility checker from Access for All.
The US Committee for PDF/UA has been busy as well. Since publishing PDF/UA in 2012 the committee has produced two informative supporting documents:
To help promote the efforts of software developers who commit to supporting PDF/UA, Duff Johnson, the PDF/UA US Committee chair since 2005, maintains a list of software supporting PDF/UA and a history of developments in PDF/UA on his site at duff-johnson.com.
You can buy ISO 14289 from the International Standards Organization.