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Apache2-API
    IM: vcdiff
    Date: Tue, 25 Nov 1997 18:30:05 GMT
    Cache-Control: no-store, im, max-age=30

See also the L<HTTP range request|https://tools.ietf.org/html/rfc7233> triggering a C<206 Partial Content> response.

=head2 HTTP_MULTIPLE_CHOICES (300)

See L<rfc 7231, section 6.4.1|https://tools.ietf.org/html/rfc7231#section-6.4.1> and L<rfc 5988|https://tools.ietf.org/html/rfc5988> for the C<Link> header.

See L<Mozilla documentation|https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/300>

This is returned when there is a redirection with multiple choices possible. For example:

    HTTP/1.1 300 Multiple Choices
    Server: Apache/2.4
    Access-Control-Allow-Headers: Content-Type,User-Agent
    Access-Control-Allow-Origin: *
    Link: </foo> rel="alternate"
    Link: </bar> rel="alternate"
    Content-Type: text/html
    Location: /foo

However, because there is no standard way to have the user choose, this response code is never used.

=head2 HTTP_MOVED_PERMANENTLY (301)

See L<rfc 7231, section 6.4.2|https://tools.ietf.org/html/rfc7231#section-6.4.2>

This is returned to indicate the target resource can now be found at a different location and all pointers should be updated accordingly. For example:

    HTTP/1.1 301 Moved Permanently
    Server: Apache/2.4
    Content-Type: text/html; charset=utf-8
    Date: Mon, 18 Apr 2022 17:33:08 GMT
    Location: https://example.org/some/where/else.html
    Keep-Alive: timeout=15, max=98
    Accept-Ranges: bytes
    Via: Moz-Cache-zlb05
    Connection: Keep-Alive
    Content-Length: 212

    <!DOCTYPE html>
    <html><head>
    <title>301 Moved Permanently</title>
    </head><body>
    <h1>Moved Permanently</h1>
    <p>The document has moved <a href="https://example.org/some/where/else.html">here</a>.</p>
    </body></html>

See also C<308 Permanent Redirect>

=head2 HTTP_MOVED_TEMPORARILY (302)

See L<rfc 7231, section 6.4.3|https://tools.ietf.org/html/rfc7231#section-6.4.3>

This is returned to indicate the resource was found, but somewhere else. This is to be understood as a temporary change.

The de facto standard, divergent from the original intent, is to point the client to a new location after a C<POST> request was performed. This is why the status code C<307> was created.

See also C<307 Temporary Redirect>, which more formally tells the client to reformulate their request to the new location.

See also C<303 See Other> for a formal implementation of aforementioned de facto standard, i.e. C<GET> new location after C<POST> request.

=head2 HTTP_SEE_OTHER (303)

See L<rfc 7231, section 6.4.4|https://tools.ietf.org/html/rfc7231#section-6.4.4>

This is returned to indicate the result of processing the request can be found at another location. For example, after a C<POST> request, such as:

    HTTP/1.1 303 See Other
    Server: Apache/2.4
    Location: /worked/well

It is considered better to redirect once request has been processed rather than returning the result immediately in the response body, because in the former case, this wil register a new entry in the client history whereas with the former, this would...

=head2 HTTP_NOT_MODIFIED (304)

See L<rfc 7232, section 4.1 on Conditional Request|https://tools.ietf.org/html/rfc7232#section-4.1>

This is returned in response to a conditional C<GET> or C<POST> request with headers such as:

=over 4

=item L<If-Match|https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/If-Match>

=item L<If-None-Match|https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/If-None-Match>

=item L<If-Modified-Since|https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/If-Modified-Since>

=item L<If-Unmodified-Since|https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/If-Unmodified-Since>

=item L<If-Range|https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/If-Range>

=back

For example:

    GET /foo HTTP/1.1
    Accept: text/html

Then, the server would reply something like:

    HTTP/1.1 200 Ok
    Content-Type: text/html
    ETag: "33a64df551425fcc55e4d42a148795d9f25f89d4"

Later, the client would do another request, such as:

    GET /foo HTTP/1.1
    Accept: text/html
    If-None-Match: "33a64df551425fcc55e4d42a148795d9f25f89d4"

And if nothing changed, the server would return something like this:

    HTTP/1.1 304 Not Modified
    ETag: "33a64df551425fcc55e4d42a148795d9f25f89d4"

=head2 HTTP_USE_PROXY (305)

See L<rfc 7231, section 6.4.5|https://tools.ietf.org/html/rfc7231#section-6.4.5> and the L<rfc 2616, section 10.3.6 deprecating this status code|https://tools.ietf.org/html/rfc2616#section-10.3.6>
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