To promote adoption of PDF/UA - the ISO standard for accessible PDF - by software developers, service bureaus and those interested in document accessibility, the PDF Association's PDF/UA Technical Working Group has developed the Matterhorn Protocol, a list of all the possible ways to fail PDF/UA-1.
The 1.1 release of the Matterhorn Protocol, released in April 2021, adds a new failure condition and provides several clarifications. The PDF file is tagged to reflect current best-practice in tagging PDF documents for accessibility and reuse.
NOTE: The Matterhorn Protocol 1.1 (PDF, 692 kB) conforms to PDF/UA-1 (ISO 14289-1) and to PDF/A-2a (ISO 19005-2), and is presented as a reference-quality PDF/UA file.
Published by the PDF Association