Digital long-term preservation aims at ensuring the long-term availability of digital documents, e.g. research data. It involves two levels. On the one hand, bitstream preservation ensures that the data remains unchanged over time. Functional long-term preservation aims at maintaining the interpretability of the data and can include measures such as migration or emulation. RADAR guarantees the readability of the datasets within the retention period specified by the customer (5-15 years) for archived datasets or for at least 25 years for published datasets. To ensure that the data can be interpreted and used, RADAR recommends the use of suitable file formats. For further information on suitable file formats, please refer to this overview.