At first sight, employing established standards, i.e. schemas or file formats, appears to be particularly sustainable to achieve ELN interoperability, regardless of the interfaces of the respective software. While this approach for ELN software with less structured content offers satisfactory solutions in the medium term, applying it to very discipline-specific ELNs with a high degree of structure becomes a complex undertaking that cannot currently be completed to satisfaction. The main reason for this is the inability of a schema to cover all specifications for the diverse contents of discipline-specific documentation, which consequently cannot be transferred clearly and in detail from one ELN to another by a data exchange format. In order to develop satisfactory solutions for those discipline-specific ELNs, for example, an Application-Programming-Interface-based (API-based) exchange of information should be considered.