SDAC - Standard for Documentation of Astronomical Catalogues
The Standard for Documentation of Astronomical Catalogues is a set of conventions for archiving astronomical data. As well as path, filename and data format conventions, it also specifies how to construct a plain text description file for documenting the data files. It was developed as an alternative to FITS that would be more suited to archives, permit human inspection, and allow manipulation via standard Unix command-line tools.
SDAC was developed by CDS (Centre de Données astronomiques de Strasbourg). Version 2.0 is the most recent; it was released in February 2000.