Generalised internal representation of a single HTTP header field. The field's value may be contained as raw data as received by HTTP, or in a object-oriented parsed form, which is accessible to the client via the class API.

Each field has a type and a (potentially complex) value. The type must be chosen at construction time, and remains the same during the header's lifetime.

Simple headers are represented using a single 'part'. Several factory methods are provided for each type the part can take; e.g.

	Max-Forwards: 3							-- a single integer value
	Location: http://ayg.com/				-- a single string token value
	Expires: Mon, 15 Jan 2001 10:30:25 GMT	-- a single date/time value
	

More complex headers are possible (see the RFC2116 for many more examples) which are built up from several parts; e.g.

	Accept: text/wml, application/vnd.wap.wmlc	-- a header with two string token parts
	Allow: GET, POST, HEAD						-- a header with three string token parts
	

Multiple parts are supported by the CHeaderFieldPart class.

Furthermore, some headers allow parameters to be supplied in the form of attribute-value pairs. These may be present on any part of the header, according to the syntax defined in the RFC; e.g.

	Accept-Charset: utf-8; q=0.8, us-ascii; q=0.2
	Cache-Control: maxage=6000
	

Parameters are supported by the CHeaderFieldParam class.

The classes CHeaderField, CHeaderFieldPart and CHeaderFieldParam are internal header representations and will only be manipulated by protocol handlers and filters. Only the RHTTPHeaders and THTTPHdrVal classes are intended for use by the Client. RHTTPHeaders THTTPHdrVal CHeaderFieldPart CHeaderFieldParam