This is not only necessary for the community in general, but it also ensures that the instruments are used to study the most relevant problems and thus increases the scientific output of the mission. A gamma ray mission open to the astronomical community at large requires that the data will be calibrated and prepared so as to be understood by non-specialists. It is hosted by the Observatory of Geneva and started its activities in 1996. Gamma-ray instruments are complex and the data reduction and calibration rest on a detailed knowledge of the instruments. The ISDC software system is made of data structures, analysis executables, pipelines and applications.
Data structures are tables and multidimensional arrays stored in FITS files.
The data structures, raw to processed, that correspond to a pointing will be grouped together. All those data structures will be grouped in a hierarchy that is described in the data themselves. In addition to the standard groups created for the proposed observations, any group of pointings can be created for archival studies. Analysis executables are C or F90 programs reading their inputs from and writing their outputs to the FITS files and reading their parameters from IRAF parameter files. Analysis executables are standalone and do not require any other software to run.