Single on Where ten HTTP header fields are defined

I found where all ten fields are defined, in four RFCs. Every quote below comes from the RFC Editor's HTML copy of the RFC and was copied from the page text I opened.

RFC 9111 (HTTP Caching), https://www.rfc-editor.org/rfc/rfc9111.html

• Age: Section 5.1, "Age"
• Cache-Control: Section 5.2, "Cache-Control"
• Expires: Section 5.3, "Expires"

RFC 9110 (HTTP Semantics), https://www.rfc-editor.org/rfc/rfc9110.html

• Last-Modified: Section 8.8.2
• ETag: Section 8.8.3
• Location: Section 10.2.2
• Retry-After: Section 10.2.3
• Vary: Section 12.5.5

RFC 6797 (HTTP Strict Transport Security), https://www.rfc-editor.org/rfc/rfc6797.html

• Strict-Transport-Security: Section 6.1, "Strict-Transport-Security HTTP Response Header Field"

RFC 8288 (Web Linking), https://www.rfc-editor.org/rfc/rfc8288.html

• Link: Section 3, "Link Serialisation in HTTP Headers." Its header says "Obsoletes: 5988", so the older RFC 5988 doesn't count.

Whether these RFCs are still current: I didn't open any page listing what currently obsoletes each RFC, such as the rfc-editor.org/info pages. The RFC texts themselves only list what they replace, not what later replaced them. So the claim that none of these four has since been obsoleted is my own knowledge and isn't backed by a source I opened. In the pages I did read, nothing contradicted it, and the sources didn't disagree on any field.

{"answers":[
{"field":"Age","rfc":"9111","section":"5.1","quote":"The \"Age\" response header field conveys the sender's estimate of the time since the response was generated or successfully validated at the origin server.","url":"https://www.rfc-editor.org/rfc/rfc9111.html"},
{"field":"Cache-Control","rfc":"9111","section":"5.2","quote":"The \"Cache-Control\" header field is used to list directives for caches along the request/response chain.","url":"https://www.rfc-editor.org/rfc/rfc9111.html"},
{"field":"Expires","rfc":"9111","section":"5.3","quote":"The \"Expires\" response header field gives the date/time after which the response is considered stale.","url":"https://www.rfc-editor.org/rfc/rfc9111.html"},
{"field":"Last-Modified","rfc":"9110","section":"8.8.2","quote":"The \"Last-Modified\" header field in a response provides a timestamp indicating the date and time at which the origin server believes the selected representation was last modified, as determined at the conclusion of handling the request.","url":"https://www.rfc-editor.org/rfc/rfc9110.html"},
{"field":"ETag","rfc":"9110","section":"8.8.3","quote":"The \"ETag\" field in a response provides the current entity tag for the selected representation, as determined at the conclusion of handling the request.","url":"https://www.rfc-editor.org/rfc/rfc9110.html"},
{"field":"Location","rfc":"9110","section":"10.2.2","quote":"The \"Location\" header field is used in some responses to refer to a specific resource in relation to the response.","url":"https://www.rfc-editor.org/rfc/rfc9110.html"},
{"field":"Retry-After","rfc":"9110","section":"10.2.3","quote":"Servers send the \"Retry-After\" header field to indicate how long the user agent ought to wait before making a follow-up request.","url":"https://www.rfc-editor.org/rfc/rfc9110.html"},
{"field":"Vary","rfc":"9110","section":"12.5.5","quote":"The \"Vary\" header field in a response describes what parts of a request message, aside from the method and target URI, might have influenced the origin server's process for selecting the content of this response.","url":"https://www.rfc-editor.org/rfc/rfc9110.html"},
{"field":"Strict-Transport-Security","rfc":"6797","section":"6.1","quote":"The Strict-Transport-Security HTTP response header field (STS header field) indicates to a UA that it MUST enforce the HSTS Policy in regards to the host emitting the response message containing this header field.","url":"https://www.rfc-editor.org/rfc/rfc6797.html"},
{"field":"Link","rfc":"8288","section":"3","quote":"The Link header field provides a means for serialising one or more links into HTTP headers.","url":"https://www.rfc-editor.org/rfc/rfc8288.html"}
]}