Recently, the IUCr (International Union of Crystallography) initiated the formation of a Diffraction Data Deposition Working Group with the aim to develop standards for the representation of raw diffraction data associated with the publication of structural papers. Reports and minutes of DDDWG meetings can be found at forums.iucr.org. Archiving of raw data serves several goals: to improve the record of science, to verify the reproducibility and to allow detailed checks of scientific data, safeguarding against fraud or to allow reanalysis with future improved techniques. In a special series of papers on 'Archiving raw crystallographic data', we reported on our experience of transferring and archiving raw diffraction data and on the problems encountered with acquiring and deciphering sufficient metadata. To be able to process the raw data one needs information on the pixel geometry, information on pixel wise corrections applied, on beam polarization, wavelength and detector position amongst others, which are ideally contained in the image header. We will demonstrate that often one needs prior knowledge, evidently of how to read the (binary) detector format, but also on the set-up of goniometer geometries. This raises concerns with respect to long-term archiving of raw diffraction data. Care has to be taken that in the future unambiguous information is available i.e. one cannot simply 'deposit the raw data' without such metadata details. We made available a local raw X-ray diffraction images data archive at the Utrecht University (rawdata.chem.uu.nl), subsequently mirrored at the Tardis Raw Diffraction Data Archive in Australia, and since March 2015 made available through digital object identifiers (DOI) at the eScholar University of Manchester Library data archive. Since 2013 approximately 150 GB of data was retrieved from our archive and some of the data sets were reprocessed by other groups.