PDF accessibility guide
PDF/UA validation: machine checks vs human review
PDF/UA includes formal requirements that software can evaluate, alongside outcomes that depend on meaning and reading experience. A useful audit separates those categories instead of flattening them into one score.
Formal machine rules
A compatible standards engine can test structural conditions exposed by the file. Record the engine, rule and result so the evidence can be reproduced.
Unavailable is not passed
If the formal engine is missing or a condition cannot be tested from the document, label it not testable. Never convert absence of evidence into success.
Meaning needs a person
Software can detect that an Alt entry exists, but it cannot reliably prove that the description conveys the image's purpose in context.
Keep the final gate explicit
Use the audit to plan remediation and review, then document who confirmed reading order, visual meaning and the intended assistive-technology experience.