The history of binary tables illustrates many of the aspects of the way in which additions to the FITS format have developed in the past and are likely to continue to evolve in the future. The initial concept for a structure typically arises from the designer of a data set who finds that none of the existing standard or proposed FITS formats will organize the data properly. A proposal is developed and a name chosen for the new extension type. This name must then be registered with the IAUFWG. It must be different from any name previously registered. The FITS Support Office maintains a list of the registered extension type names and will forward name registration requests to the IAUFWG. In some cases, a temporary local form of the extension with a different name will be be defined as well. This local name must also be registered with the IAUFWG. The local or developmental form may serve as the basis for designing data sets elsewhere while the full proposal is being developed, as occurred with A3DTABLE. During this period, the developer will discuss concepts of this new extension with others interested in the format and may modify it based on this discussion.
Eventually, a formal proposal will be made available for review by the astronomical community, normally by announcing World Wide Web (WWW) and ftp locations where it can be obtained. With the more general use of FITS and the increasing ease of electronic transmission of documents, proposals are becoming available to a wider public at earlier stages than was the case during the early days of FITS. Tests are run using the new format to confirm that it can be practically used for data transport. After the community has reviewed the proposal, any modifications have been made, and the format has been successfully used for data transport, the proposal is submitted for approval to the regional committees--the European FITS Committee, the Japanese FITS Committee, and the American Astronomical Society Working Group on Astronomical Software (WGAS) FITS Committee. Following approval by the regional committees, it is submitted to the IAUFWG. Approval by the Working Group establishes it as a standard extension.
A number of aspects of this process are worth noting. First, FITS formats have been developed through the efforts of individuals responding to particular practical problems. Although there is extensive community review, most of the initial detailed development is done by the people who actually need to use a format for a particular purpose, rather than by a formal committee. A new format must be demonstrated to work in practice through actual data transport before it can be approved as standard, ensuring that the standard is not purely theoretical but has actually been used. Finally, the approval process occurs by community consensus, as is customary in the world of standards.