The following list shows error codes sent by http servers
and are provided for reference only.
Thanks to Wolf Z. Maas for the information.

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0   Unknown Error
200 OK
201 Created
202 Accepted
203 Partial Information
204 No Response
301 Moved
302 Found
303 Method
304 Not Modified
400 Bad Request
401 Unauthorized
402 PaymentRequired
403 Forbidden
404 Not Found
500 Internal Error
501 Not Implemented
502 Service Temporarily Overloaded
503 Gateway Timeout
600 Bad Request in Client
601 Not Implemented in Client
602 Connection Failed
603 Timed Out
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