2. The Cache-Groups Response Header Field

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Original RFC Text

2.  The Cache-Groups Response Header Field

   The Cache-Groups response header field is a List of Strings (Sections
   3.1 and 3.3.3 of [STRUCTURED-FIELDS]).  Each member of the List is a
   value that identifies a group that the response belongs to.  These
   Strings are opaque -- while they might have some meaning to the
   server that creates them, the cache does not have any insight into
   their structure or content (beyond uniquely identifying a group).

   HTTP/1.1 200 OK
   Content-Type: application/javascript
   Cache-Control: max-age=3600
   Cache-Groups: "scripts"

   The ordering of members is not significant.  Unrecognised Parameters
   are to be ignored.

   Implementations MUST support at least 32 groups in a field value,
   with up to at least 32 characters in each member.  Note that generic
   limitations on HTTP field lengths may constrain the size of this
   field value in practice.