Some Web page code hints mean:

? 100-Continue.
? 101-Switch protocol.
? 110 Restart Tag reply.
? 120 service is ready, starting in nnn minutes.
? 125 The data connection is open and the transfer is starting.
? 150 file status OK, ready to open data connection.
? 200-OK. The client request was successful.
? 201-created.
? 202-accepted.
? 203-Non-authoritative information.
? 204-no content.
? 205-Reset the content.
? 206-Partial content.
? 211 System Status, or system help reply.
? 212 Directory status.
? 213 file status.
? 214 Help message.
? 215 Name System type, where name is the formal system name listed in the Assigned Numbers document.
? 220 The service is ready to execute the request of the new user.
? 221 Service closes the control connection. If appropriate, please log out.
? 225 Data connection Open, no in-progress transfer.
? 226 Close the data connection. The requested file operation was successful.
? 227 Enter passive mode (H1,H2,H3,H4,P1,P2).
? 230 The user is logged in and continues.
? 250 The requested file operation is correct and completed.
? 257 "PATHNAME" has been created.
? 302-The object has been moved.
? 304-not modified.
? 307-Temporary redirection.
? 332 You need to log in to your account.
? 350 The requested file operation is waiting for further information.
? 400-Bad request.
? 401-access is denied.
? 401.2-The server configuration caused the login to fail.
? 401.3-not authorized due to ACL restrictions on resources.
? 401.4-Filter Authorization failed.
? 401.5-ISAPI/CGI application authorization failed.
? 401.7– access is denied by the URL authorization policy on the WEB server. This error code is specific to IIS 6.0.
? 403-No access.
? 403.1-execution access is forbidden.
? 403.2-Read access is forbidden.
? 403.3-Write access is forbidden.
? 403.4-Requires SSL.
? 403.5-Requires SSL 128.
? The 403.6-IP address is rejected.
? 403.7-Requires a client certificate.
? 403.8-site access is denied.
? 403.9-Excessive number of users.
? 403.10-Invalid configuration.
? 403.11-Password change.
? 403.12-Deny access to the mapping table.
? 403.13-The client certificate is revoked.
? 403.14-Reject directory list.
? 403.15-Client access permission exceeded.
? 403.16-Client certificate is not trusted or invalid.
? 403.17-The client certificate has expired or is not yet valid.
? 403.18-The requested URL cannot be executed in the current application pool. This error code is specific to IIS 6.0.
? 403.19-CGI cannot be executed for clients in this application pool. This error code is specific to IIS 6.0.
? 403.20-passport Login failed. This error code is specific to IIS 6.0.
? 404-Service resource not found (Web page not found)
? 404.0-(None) – No files or directories found.
? 404.1-Unable to access the WEB site on the requested port.
? The 404.2-web service extension lockout policy blocks this request.
? The 404.3-mime mapping policy blocks this request.
? 405-The HTTP verb used to access this page is not allowed (method not allowed)
? 406-The client browser does not accept the MIME type of the requested page.
? 407-proxy authentication is required.
? 412-Precondition failed.
? 413– request entity is too large.
? 414-The request URI is too long.
? 415– media types not supported.
? The range requested by 416– is not sufficient.
? 417– execution failed.
? 423– a locked error.
? 425 The data connection cannot be opened.
? 426 Connection closed; Transfer aborted.
? 450 The requested file operation was not performed. The file is not available (for example, the file is busy).
? 451 requested operation aborted: Local error is being processed.
? 452 the requested operation was not performed. The system does not have enough storage space.
? 500-Internal server error (server in error).
? 500.12-The application is busy restarting on the WEB server.
? The 500.13-web server is too busy.
? 500.15-Direct Request Global.asa is not allowed.
? 500.16–unc authorization credentials are incorrect. This error code is specific to IIS 6.0.
? The 500.18–url authorization store cannot be opened. This error code is specific to IIS 6.0.
? 500.100-Internal ASP error.
? 501-The header value specifies the configuration that is not implemented.
? An invalid response was received when the 502-web server was used as a gateway or proxy server. The 502.1-cgi application timed out.
? 502.2-CGI Application error. Application.
? 503-The service is not available. This error code is specific to IIS 6.0.
? 504-The gateway timed out.
? 505-http version is not supported.
? 530 not logged in.
? 532 The account is required to store the file.
? 550 the requested operation was not performed. The file is not available (for example, the file was not found and no access was granted).
? 551 requested operation aborted: unknown page type.
? 552 requested file operation terminated abnormally: storage allocation exceeded (for current directory or dataset).
? 553 The requested operation was not performed. The file name is not allowed.

Some Web page code hints mean: