Handle to the basic stream object.

Members:

IG_PDF_basstream_create	Creates a new stream object associated with the specified document and having the specified value.
IG_PDF_basstream_get_dict	Gets a stream’s attributes dictionary.
IG_PDF_basstream_get_value	Copies at most nBufferLenbytes from object's stream value into lpBuffer, and stores the actual length of the basic string in lpnStreamLen.