On August 4, 2013, the PDF Association issued the Matterhorn Protocol, establishing formal validation criteria for conformance with PDF/UA. The Matterhorn Protocol lists all the possible ways to fail the precise technical specifications provided in ISO standard 14289 (PDF Universal Accessibility):
- 136 failure conditions
- 89 can be determined by automated testing alone
- Manual inspection and knowledgeable human judgment are essential for evaluating the remaining 47 conditions
The Matterhorn Protocol promotes adoption of PDF/UA by software developers and document remediators, bringing the substantial benefits of PDF/UA closer to reality.