Header Fields

The "where" column describes the request and response types in which the header field can be used.Values in this column are:

Requests: header field may only appear in requests
Responses: header field may only appear in responses

2xx, 4xx, etc.: A numerical value or range indicates response codes with which the header field can be used;

Copied: header field is copied from the request to the response.

An empty entry in the "where" column indicates that the header field may be present in all requests and responses.