The Research and Documentation Centre (WODC) of the Dutch Ministry of Security and Justice uses a lot of different, heterogeneous, data sets in their research. The need for integration depends strongly on the research being done, which is why the data sets are managed using a data space approach. In this approach, mappings are used to transform data sets such that they are useful for specific research projects and therefore volatile and highly flexible. Insight in these mappings and especially why they are performed is essential to understand the research data set. So, besides data provenance of the data itself, the WODC is also interested in storing the associated knowledge in a transparant yet maintainable way.