The TCN HTTP header — content negotiation, RFC 2295, not observed in the catalog.
TCN
Content Negotiation 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.
TCN is content negotiation — Headers through which client and server agree on representation: media type, language, encoding, character set.
The registry
Listed in the IANA HTTP Field Name Registry as a permanent entry. Defined in RFC 2295: Transparent Content Negotiation in HTTP.
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 →