Heritage projects, archivization and re-usability concerns

FCC is a long term project. In many respects novel, and new calculations including simulation programs will be appearing in the forthcoming years. However, many of the approaches developed for the previous experiments, in particular LEP will be useful, either directly as a tools or as a means to prepare substantial benchmarks. Also programs which will be prepared for Belle II, especially in domain of τ , B and D resonance physics will continue to be valuable tools. Such programs and projects will undoubtedly evolve in the mean time, but one can expect that ready to use versions will be available when the need will arrive. Then only interfaces will need to be archived solely for the FCC need. In some cases the whole projects will require long term archivization. Before we will explain some attempts on archivization of some example projects, such as τ decays, radiative corrections in decays or electroweak corrections, let us mention general possible approaches. There are many tools helpful to manage software projects: development and archivization. However, archivization-development tools become obsolete and code history, necessarily for future extensions and validation may become lost and therefore it is important to ensure proper migration from one archivization-development to the other. In addition, very stable solutions belong to repositories outside of authors responsibility and specifically targeting long term of archivization.