$request->QueryInfo(header, [flags])
Queries information about an HTTP request object ($request) created
with OpenRequest. You can specify a header
(for example, "Content-type") and/or one or more flags.
If you don't specify flags, HTTP_QUERY_CUSTOM will be used
by default; this means that the header should contain a valid HTTP
header name. For the possible values of flags, refer to the
Microsoft Win32 Internet Functions documentation.