The conversion of the internal data representation of the ISDAT system into IDFS data format is described. We present the internal data representation of ISDAT system as software data format and IDFS as file data format. We split the conversion into three parts -- the conversion of the data definition key, conversion of the data and conversion of metadata. We give a possible design of a fully automated process of the data conversion from ISDAT to IDFS. 1 Introduction In this paper we describe the conversion of the internal data representation of ISDAT system to IDFS data format. This problem arose naturally during the planning of storage of data from the CLUSTER project. Some of the data will be accessible through the ISDAT system 1 and other data will be stored using the SDDAS system. Scientists would like the possibility of plotting simultaneously data from different systems, for which the transfer of data between the two systems is needed. Moreover, when the problem of the c..