How to use this reference
Model window references separately from origin-wide data and service authority. For an owned application, document every shared client capability and server data path before relying on opener separation; combine appropriate embedding, cookie and response controls with an explicit trust-domain design.
Before reading
- Browser origin and navigation concepts
- HTTP session and response-cache fundamentals
Context and limits
- A specification defines intended behavior; this review does not establish per-value support in deployed browsers.
- Opener separation alone does not partition origin-wide storage or grant application-level authorization.
- This resource complements message validation and request-context resources by modeling the isolation boundary itself.
Sources and provenance
- HTML Standard: Cross-origin opener policies WHATWG · reviewed 2026-10-03
Record reviewed 2026-10-03. Snapshot d5550c789111. Open the complete JSON contract.