The Trailer HTTP header — connection & transport, RFC 9110, not observed in the catalog.
Trailer
Connection & Transport 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.
Trailer is connection & transport — Headers about the connection rather than the resource: hosts, upgrades, proxies, forwarding, keep-alive.
The registry
Listed in the IANA HTTP Field Name Registry as a permanent entry. Defined in RFC 9110, Section 6.6.2: HTTP Semantics.
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 →