What a VPAT and ACR are
VPAT means Voluntary Product Accessibility Template. ACR means Accessibility Conformance Report. One is the form, one is the answer.
The form
The ITI publishes the VPAT template. It lists standards and their criteria in tables: WCAG (Web Content Accessibility Guidelines), Section 508 chapters, EN 301 549 clauses. Empty, it proves nothing.
The filled report
An ACR is that template completed for one product version. Each row carries a rating, Supports, Partially Supports or Does Not Support, plus remarks saying what passes and what fails. Buyers read the remarks, not just the ratings.
What each row must prove
Every rating needs evidence from real testing: which pages, which assistive technology, which version. A row without evidence fails procurement review. That is why testing comes before the report, never after.