The Cross-Origin-Opener-Policy HTTP header — security policy, not observed in the catalog.
Cross-Origin-Opener-Policy
Security Policy IANA permanent
A reference entry. The registry facts and catalog measurements below are complete; the written guidance for this header has not been authored yet.
Cross-Origin-Opener-Policy is security policy — Response headers instructing the client to constrain itself — transport security, framing, script sources, sniffing, referrer leakage.
The registry
Listed in the IANA HTTP Field Name Registry as a permanent entry. Defined in HTML. It is a structured field of type Item (RFC 9651).
In the catalog
Registered with IANA and declared by not one of the 26,641 providers in the API Evangelist catalog. A registered field with no observed use is still part of the vocabulary — it just is not part of the practice.
Governed by these rules
Machine-enforceable governance rules from rules.apievangelist.com that apply to this header when it appears in an OpenAPI.
OpenAPI Components Headers Error error
Utilizing the headers object in the centralized OpenAPI components library helps make headers reusable across API requests and responses
Guidance: Rate Limits →OpenAPI Components Headers Info info
Utilizing the headers object in the centralized OpenAPI components library helps make headers reusable across API requests and responses
Guidance: Rate Limits →OpenAPI Headers Hyphenated Pascal Case error
HTTP headers should follow Hyphenated-Pascal-Case naming convention for consistency and readability, such as Content-Type, X-Request-Id, or Accept-Language.
Guidance: Naming →