Character you use to group keys. 
            
 Declaration Syntax
 Declaration Syntax| C# | 
public string Delimiter { get; set; }
 Remarks
 Remarks
            All keys that contain the same string between the prefix, 
            if specified, and the first occurrence of the delimiter 
            after the prefix are grouped under a single result element, 
            CommonPrefixes. If you don't specify the prefix parameter, 
            then the substring starts at the beginning of the key. The 
            keys that are grouped under CommonPrefixes result element 
            are not returned elsewhere in the response.