LEVEL_500         724 modules/http/http_protocol.c     LEVEL_500, RESPONSE_CODES};
LEVEL_500         728 modules/http/http_protocol.c         return LEVEL_500;
LEVEL_500         739 modules/http/http_protocol.c                 return LEVEL_500;            /* status unknown (falls in gap) */
LEVEL_500         743 modules/http/http_protocol.c     return LEVEL_500;                         /* 600 or above is also illegal */