Pathlines are used. Due to the limitations of some current software, the Backbone can not guarantee delivery of messages in excess of 13,000 bytes. Hubs are encouraged to use message processing software which allows larger messages, preferably up to 64K bytes, to be handled. Hubs may delete messages which do not conform to the technical standards set forth in this Section when such messages might be harmful to the technical operation of the Backbone. Such messages are generally not returned.
Hubs operate in a secure fashion.
They automatically process inbound messages only from those nodes with which prior agreements have been made. However, any reasonable method of ensuring that non-secure messages do not enter the Backbone is acceptable. A Hub may choose not to provide services to a Node which does not operate in a secure fashion if this Node has a history of causing problems due to this lack of security. The ZBC normally requires that the conference has achieved some degree of distribution before accepting this request. At least three RBCs request that the Backbone distribute the conference to their regions.