IdHTTPHeaderInfo

TIdEntityHeaderInfo is a TPersistent descendant that represents message headers from a HTTP request or response, as described in the Internet Standards document: 

RFC 2616 - Hypertext Transfer Protocol version 1.1 [HTTP/1.1]  

TIdEntityHeaderInfo is the ancestor class that defines the common headers used in TIdRequestHeaderInfo and TIdResponseHeaderInfo, and represents header fields that define metainformation about the entity body or, if no body is present, about a resource associated with a request. Some of this metainformation is optional; some headers might be required dependent on the HTTP protocol specification. 

Applications will normally create instances of TIdRequestHeaderInfo or TIdResponseHeaderInfo, which implement the contextual semantic requirements for the HTTP protocol.

TIdRequestHeaderInfo 

TIdResponseHeaderInfo