WCAG 2.2 AA
The baseline
The success criteria every other rule points at: alt text, contrast, headings, reading order and keyboard-navigable structure.
ADA Title II / III
The US mandate
US public bodies and businesses open to the public must make their digital documents usable by people with disabilities.
Section 508
US federal
Anything bought, built or published by a US federal agency has to meet accessibility standards, training decks included.
EN 301 549
The European spec
The technical standard EU law points to. It folds WCAG into public procurement, so non-compliant documents lose you bids.
EAA
The new deadline
The European Accessibility Act pulls customer-facing documents of private companies into scope: statements, contracts, manuals.
PDF/UA
The file format
The ISO standard for how an accessible PDF is built on the inside: tags, reading order and metadata a screen reader can follow.