Typically there are only a few status codes that you should see when using the WEB Access Library, which are broken down as follows:
Group  | 
Meaning  | 
200-299  | 
Success  | 
300-399  | 
Information  | 
400-499  | 
Request error  | 
500-599  | 
Server error  | 
The most common codes are:
Status code  | 
Meaning  | 
200  | 
URL located, transmission follows  | 
400  | 
Unintelligible request  | 
404  | 
Requested URL not found  | 
405  | 
Server does not support requested method  | 
500  | 
Unknown server error  | 
503  | 
Server capacity reached  | 
The full list of status codes has been extracted from the Microsoft Header file and is listed here.