PDF / A-1b +可访问性是否等同于PDF / A-1a？

Question

we are creating accessible PDFs through our software. Currently, we are complaint with PDF/A-1b standard. Recently, we have started supporting accessibility also(compliant with Matterhorn Protocol). So can we now say our PDFs produced are PDF/A-1a compliant ? (assume all PDF/A-1b features are supported and new PDFs are PDF/UA compliant as per matterhorn protocol)

PS: I tried online PDF/A validators but they are not reliable. I am saying this because I tried their tools with PDF/A-1a compliant files (matterhorn reference PDF files) that are used as reference files by developer/testers, were also marked non-compliant by those tools. So i am looking for a quick answer so that I don't have to go through long process of finding a reliable validator (plus that might be a paid software :) ).

Answer 1

This question is confusing PDF/A , PDF/UA , and their intersection.

To clear things up, PDF/A-1 refers to the ISO 19005-1 specification from 2005, which places additional requirements and restrictions on the PDF version 1.4 specification to make PDF documents suitable for long term archiving. PDF/A-2 refers to the ISO 19005-2 specification from 2011 which re-bases the PDF/A specification off of the ISO 32000-1:2008 version of the PDF v1.7 specification.

PDF/UA-1 refers to the ISO 14289-1 specification from 2012 which places additional requirements and restrictions on the ISO 32000-1:2008 specification to make PDF documents accessible for assistive technology.

It is possible, but not necessarily easy, to make a PDF v1.7 document comply to both PDF/UA-1 and PDF/A-2 so that it is both accessible and ready for long-term archiving.

However, it is also possible to make a PDF/A document that can't ever conform to PDF/UA. PDF/A has conformance levels a and b (ignoring u) where the essential difference is that 'a' requires that a PDF document be tagged, while 'b' does not.

Tagged PDF is discussed in section 14.8 of the ISO 32000-1:2008 PDF specification, it builds upon sections 14.6 (Marked Content) and 14.7 (Logical Structure).

Note that the following section ( 14.9 Accessibility Support) is also of interest as the PDF/UA specification is all about accessibility and builds on top of all of these sections of the PDF specification: PDF/UA (among other requirements) essentially requires all content elements in a PDF to be tagged to be conformant.