What are Conformance Levels
Conformance Levels refer to the specific set of rules and requirements defined in the corresponding PDF ISO subset. Each Conformance Level is represented by a letter designator with a PDF ISO subset acronym, such as PDF/A-1b or PDF/X-5pg.
For instance, PDF/A-4e is a highly specialized refinement of PDF-for-archival standard supporting engineering workflows with 3D content, while PDF/A-2b and PDF/A-2u differ in their Unicode text extraction capabilities.
It is important to note that not all PDF ISO subsets use conformance levels. PDF/A, PDF/X, and PDF/VT are the ISO subsets of PDF that use conformance levels to define different levels of compliance with the standard. Other ISO subsets such as PDF/UA (for accessibility) and PDF/E (for engineering) also have their own requirements, but they do not use conformance levels in the same way.
For more information on PDF/A Conformance Levels and their requirements, please refer to our comprehensive article on the topic: PDF/A – the ISO standard for long-term archiving