The process of assuring interoperability of data is focused on making sure that data can be processed by different systems. Differently from data standardisation, there is no expectation that data are formatted in the same way (i.e., following the same standards), but data are marked up with the necessary contextual information to allow a machine (a computer, or an analysis system) to understand its meaning and how it can be combined to data from other sources. In the OH context, data interoperability is concerned with making sure that data produced across different health dimensions (food, animal, public and environmental health), and by different actors, can be used within the same surveillance system.