... Winkelman, S. L., Rots, A. H., Michaud, K., & Blecksmith, S. E. 2003, in ASP Conf. ... We have collected the complete body of FITS keywords, as used in Chandra data products, into a dictionary database that provides easy access to their use and meaning. ... For the Chandra Data Archive almost all data products are in FITS format, following a stringent set of conventions concerning the data formats and header construction. ... A filetype is composed of one or more Header-Data Units (HDU). ...