A general broadcast through the Internet is achieved by setting the sa_netnum and sa_nodenum fields to binary 1's (-1). The service provider translates this request to a 'type 20 packet', which IPX routers recognize and forward. Your packet will visit all subnets and may be duplicated several times. Receivers must handle several duplicate copies of your datagram.
Use of this broadcast type is very unpopular among network administrators and its use should be extremely limited. Many routers disable this type of broadcast, leaving parts of the subnet invisible to your packet.