Index: wp-includes/functions.php
===================================================================
--- wp-includes/functions.php	(revision 19601)
+++ wp-includes/functions.php	(working copy)
@@ -1588,61 +1588,85 @@
 
 	if ( !isset( $wp_header_to_desc ) ) {
 		$wp_header_to_desc = array(
-			100 => 'Continue',
-			101 => 'Switching Protocols',
-			102 => 'Processing',
+			100 => 'Continue', # RFC2616
+			101 => 'Switching Protocols', # RFC2616
+			102 => 'Processing', # RFC2518
+			103 => 'Checkpoint', # Resumable HTTP Requests Proposal
+			# 104-121 Unassigned
+			122 => 'Request-URI too long', # Non-standard IE7-only code
 
-			200 => 'OK',
-			201 => 'Created',
-			202 => 'Accepted',
-			203 => 'Non-Authoritative Information',
-			204 => 'No Content',
-			205 => 'Reset Content',
-			206 => 'Partial Content',
-			207 => 'Multi-Status',
-			226 => 'IM Used',
+			200 => 'OK', # RFC2616
+			201 => 'Created', # RFC2616
+			202 => 'Accepted', # RFC2616
+			203 => 'Non-Authoritative Information', # RFC2616
+			204 => 'No Content', # RFC2616
+			205 => 'Reset Content', # RFC2616
+			206 => 'Partial Content', # RFC2616
+			207 => 'Multi-Status', # RFC4918
+			208 => 'Already Reported', # RFC5842
+			# 209-225   Unassigned
+			226 => 'IM Used', # RFC3229
 
-			300 => 'Multiple Choices',
-			301 => 'Moved Permanently',
-			302 => 'Found',
-			303 => 'See Other',
-			304 => 'Not Modified',
-			305 => 'Use Proxy',
-			306 => 'Reserved',
-			307 => 'Temporary Redirect',
+			300 => 'Multiple Choices', # RFC2616
+			301 => 'Moved Permanently', # RFC2616
+			302 => 'Found', # RFC2616
+			303 => 'See Other', # RFC2616
+			304 => 'Not Modified', # RFC2616
+			305 => 'Use Proxy', # RFC2616
+			306 => 'Reserved',  # RFC2616 was 'Switch Proxy' is '(unused)' per RFC2616
+			307 => 'Temporary Redirect', # RFC2616
+			308 => 'Resume Incomplete', # Resumable HTTP Requests Proposal
 
-			400 => 'Bad Request',
-			401 => 'Unauthorized',
-			402 => 'Payment Required',
-			403 => 'Forbidden',
-			404 => 'Not Found',
-			405 => 'Method Not Allowed',
-			406 => 'Not Acceptable',
-			407 => 'Proxy Authentication Required',
-			408 => 'Request Timeout',
-			409 => 'Conflict',
-			410 => 'Gone',
-			411 => 'Length Required',
-			412 => 'Precondition Failed',
-			413 => 'Request Entity Too Large',
-			414 => 'Request-URI Too Long',
-			415 => 'Unsupported Media Type',
-			416 => 'Requested Range Not Satisfiable',
-			417 => 'Expectation Failed',
-			422 => 'Unprocessable Entity',
-			423 => 'Locked',
-			424 => 'Failed Dependency',
-			426 => 'Upgrade Required',
+			400 => 'Bad Request', # RFC2616
+			401 => 'Unauthorized', # RFC2616
+			402 => 'Payment Required', # RFC2616
+			403 => 'Forbidden', # RFC2616
+			404 => 'Not Found', # RFC2616
+			405 => 'Method Not Allowed', # RFC2616
+			406 => 'Not Acceptable', # RFC2616
+			407 => 'Proxy Authentication Required', # RFC2616
+			408 => 'Request Timeout', # RFC2616
+			409 => 'Conflict', # RFC2616
+			410 => 'Gone', # RFC2616
+			411 => 'Length Required', # RFC2616
+			412 => 'Precondition Failed', # RFC2616
+			413 => 'Request Entity Too Large', # RFC2616
+			414 => 'Request-URI Too Long', # RFC2616
+			415 => 'Unsupported Media Type', # RFC2616
+			416 => 'Requested Range Not Satisfiable', # RFC2616
+			417 => 'Expectation Failed', # RFC2616
+			418 => 'I\'m a teapot', # One of the traditional IETF April Fools' jokes, RFC2324, Hyper Text Coffee Pot Control Protocol
+			# 419-421 Unassigned
+			422 => 'Unprocessable Entity', # RFC4918
+			423 => 'Locked', # RFC4918
+			424 => 'Failed Dependency', # RFC4918
+			425 => 'Unordered Collection', # RFC2817; IANA: 'Reserved for WebDAV advanced collections expired proposal' which is 'Unordered Collection'
+			426 => 'Upgrade Required', # RFC2817
+			# 427 Unassigned
+			428 => 'Precondition Required', # Proposed in an Internet-Draft
+			429 => 'Too Many Requests', # Proposed in an Internet-Draft
+			# 430 Unassigned
+			431 => 'Request Header Fields Too Large', # Proposed in an Internet-Draft
+			# 432-443 Unassigned
+			444 => 'No Response', # An nginx HTTP server extension
+			# 445-448 Unassigned
+			449 => 'Retry With', # A Microsoft extension
+			450 => 'Blocked by Windows Parental Controls', # A Microsoft extension
+			# 451-498 Unassigned
+			499 => 'Client Closed Request', # An Nginx HTTP server extension
 
-			500 => 'Internal Server Error',
-			501 => 'Not Implemented',
-			502 => 'Bad Gateway',
-			503 => 'Service Unavailable',
-			504 => 'Gateway Timeout',
-			505 => 'HTTP Version Not Supported',
-			506 => 'Variant Also Negotiates',
-			507 => 'Insufficient Storage',
-			510 => 'Not Extended'
+			500 => 'Internal Server Error', # RFC2616
+			501 => 'Not Implemented', # RFC2616
+			502 => 'Bad Gateway', # RFC2616
+			503 => 'Service Unavailable', # RFC2616
+			504 => 'Gateway Timeout', # RFC2616
+			505 => 'HTTP Version Not Supported', # RFC2616
+			506 => 'Variant Also Negotiates', # RFC2295
+			507 => 'Insufficient Storage', # RFC4918
+			508 => 'Loop Detected', # RFC5842
+			509 => 'Bandwidth Limit Exceeded', # Apache bw/limited extension
+			510 => 'Not Extended', # RFC2774
+			511 => 'Network Authentication Required' # Proposed in an Internet-Draft
 		);
 	}