[en] Accurate knowledge of fission-product source terms during operation and following shutdown of power reactors is essential to many aspects of nuclear reactor safety and nuclear safeguards considerations. Certain fission-product source terms are also important for accurate reactivity predictions during fuel depletion, conversion, and burnup in nuclear reactor calculations. This paper summarizes research in a number of areas related to fission products. It should acquaint the reader with the scope of application of the nuclide data base and lend credence to the quality of the data. The results of data testing, data uncertainties, experimental comparisons, and work related to the analysis of decay heating are emphasized. Experimental comparisons include short-term decay heating measured at the LASL, Oak Ridge National Laboratory (ORNL), Intelcom Rad tech (IRT), and the Commissariat A l'Energie Atomique-France (CEAF). In addition, beta spectral comparisons with measurements at the University of Illinois (UI) and ORNL are included. Gamma spectra are compared with LASL and ORNL measurements. Absorption buildup in long term-irradiations experiments and photoneutron spectra have also been calculated and compared with measurements, but the work related to decay heat, analysis of experiments and spectra is emphasized