change in the DGN file format/structure from Microstation V8i SS3 to SS10

Hello, Need to know, if there was a change in the DGN file format from Microstation V8i SS3 to SS10. We have a third-party dependency which in turn has dependency on ODA, that enables us to handle Dgn files. Any previously supported Dgn files will continue to work with newer versions of Microstation select series, as long as there is no structure change to the file format. So my question above pertains to where and how can i find out of format/structure changes to v8i.