Name,Type,Description,Reference
hit,Boolean,"When true, indicates that the
        request was satisfied by the cache; that is, it was not forwarded,
        and the response was obtained from the cache.",[RFC9211]
fwd,Token,"When present, indicates that the request went forward towards
        the origin; its value indicates why.",[RFC9211]
fwd-status,Integer,"Indicates which status code (see [RFC9110], Section 15)
        the next-hop server returned in response to the forwarded request.",[RFC9211]
ttl,Integer,"Indicates the response¡¯s remaining freshness lifetime
        (see [RFC9111], Section 4.2.1)
        as calculated by the cache, as an integer number of seconds, measured as closely as possible to when
        the response header section is sent by the cache.",[RFC9211]
stored,Boolean,"Indicates whether the cache stored the response
        (see [RFC9111], Section 3); a true value indicates that it did.",[RFC9211]
collapsed,Boolean,"Indicates whether this request was collapsed together with one or more other forward
        requests (see [RFC9111], Section 4); If true, the response was successfully
        reused; if not, a new request had to be made.",[RFC9211]
key,String,"Conveys a representation of the cache key
        (see [RFC9111], Section 2) used for the response.",[RFC9211]
detail,String or Token,"Allows implementations to convey additional information not captured in
        other parameters, such as implementation-specific states or other caching-related metrics.",[RFC9211]