Principle 2 Operable · Guideline 2.2: Enough Time
2.2.5 Re-authenticating
After a session expires, work continues without data loss.
What this means in practice
Users who have to log in again should find their input intact. Filling a long form twice is where many give up.
Normative wording
The binding text lives at the W3C. What you read here is our own faithful rendering – not a quotation.