Handling of Atomic Data

State-of-the-art NLTE model-atmosphere codes have arrived at a high level of numerical sophistication and are now useful tools to analyze high-quality spectra from the infrared to the X-ray wavelength range. The capacity of current computers permit calculations which include line spectra from all elements from hydrogen up to the iron group. The lack of reliable atomic data has become a critical problem for further progress. We summarize available sources of atomic data, and discuss how these are implemented in the Tuebingen Model-Atmosphere Package TMAP. We describe our Iron Opacity Interface IrOnIc which is used to calculate opacities of iron-group elements from Kurucz's and the Opacity Project's data. We propose general use of the Tuebingen Model-Atom Database TMAD, which would allow an easy exchange of ready-to-use model atoms between all model-atmosphere groups. The comparison of model-atmosphere calculations would then be much easier, and would save a great deal of manpower that is presently consumed preparing suitable model atoms for spectral analyses.