There are already approaches to solve the ELN interoperability problem being advanced by individual providers or consortia, aiming at long-term harmonisation of research data and metadata. The group "The ELN consortium", involving developers of ELNs from academic institutions, is working towards generating a unified format (*.eln) that can be used by all participating ELNs based on the well-established RO-Crate specification. This approach has a high potential for being successful in offering data exchange solutions in the long run. Also, the ELN consortium improves the FAIRness of data due to continuous extensions of the metadata descriptions in the *.eln file, e.g. by adding further semantic annotations using JSON-LD. However, a file exchange requires high implementation effort for the ELN developers, as the transfer of specific data requires adaptation of the file format for each pair of ELNs, also keeping the format updated to newer ELN versions. Moreover, moving files induces much manual work for the users.