| Document: FSC-0090 | Version: 001 | Date: 9 December, 1995 | | Author: David Nugent, 3:632/348@fidonet FTSC Issued Product Codes by David Nugent, December 9, 1995. For many years, the FidoNet Technical Standards Committee has been issuing product codes for use in FidoNet products used on the network (specifically those products responsible for creation and exchange of data over the network; products creating FidoNet type-2 packets described in FTS-0001 and mailers talking together using FidoNet protocols described in FTS-0001, FTS-0006, FTS-0007 and FSC-0056. The primary purpose of using these product codes was not to create a registry of FidoNet related products, but to facilitate the identification of products responsible for network problems and providing a means by which authors might be contacted by the Committee should problems with a specific product be brought to its attention. Products issued with FTSC codes In respect to this objective, the results have only been partially successful. True, the product code list has been used from time to time both to identify aberrant products and also to contact authors and is still occasionally used for this purpose by both Committee members and others. The number of products which can be allocated FTSC product codes had some years ago exceeded expectation. Since FTS-0001 "type-2" FidoNet packets allocate a mere 8 bit field for the product code, that set the effective maximum number of products which could be allocated a product code to 256. All numbers had been allocated or reserved by early 1991. The issue was discussed at some length by the FTSC which debated first the worth of continuing to issue product codes, and secondly if the practice was to be continued, to effect changes in the FTS-0001 packet header format to accommodate at least a 16-bit (two- octet) product code. The first issue was resolved in favour of retaining the product codes, but as yet, now in 1995, the second issue has not been resolved by Committee members. Two of the later FSC documents submitted to the Committee had indeed allocated an additional byte for the product code, but had elected to reuse the existing product code byte as the 'lower' half of the new product code, which would cause existing products to be incorrectly identified by existing FTS-0001 compatible FidoNet implementations. The behaviour of this incorrect identification has an undefined effect. Both proposals were rejected by the Committee on that basis. FidoNet product codes are used in the following circumstances: a) by mailers during FTS-0001 sessions; session negotiation is the exchange of FTS-0001 packet headers, b) by products which create type-2 packets, c) by mailers during negotiation of FTS-0006 (YooHoo) and FSC-0056 (EMSI) sessions. FTS-0006 sessions allocate 16-bits for a product code, and FSC-0056 places no specific limits on size (although a 16-bit or 32-bit limitation might be implied and used in implementations). The conclusion from this is that FidoNet product codes are still useful to FidoNet mailers during session negotiation using FidoNet enhanced handshaking protocols. Therefore, product codes are now being issued only for mailer products with FTS-0006 and/or FSC-0056 capability. FidoNet products without an allocated product code which either create type-2 packets, or negotiate FTS-0001 sessions must use a product code x'fe or 254 in type-2 compatible packet headers. This code as been reserved for that purpose (use by product without a product code). The product code x'ff or 255 has been reserved to indicate that the product code is stored elsewhere in the packet header at an as yet unallocated offset (please do not use this as yet - this FSC will be modified accordingly when FTS-0001 is updated to designate the correct offset).