It would have been really useful for Inspector Javert to find Jean Valjean if he had the cross-references between the identifies of all of the people he met in Montreuil-sur-Mer to the prisoner database (all he needed was 24601!). Since this dataset has a long name, you can feel free to abbreviate it as IJXD. We have the same problem in bioinformatics, so this is a database of cross-references extracted from OBO Foundry and other sources by PyOBO. It is a gzipped five-column TSV file that has source namespace, source identifier, target namespace, target identifier, and provenance. Each has been normalized so cross-references from different sources can be integrated and traversed. It was generated with the following code in the shell: pip install pyobo pyobo obo xrefs More information on this blog post: https://cthoyt.com/2020/04/19/inspector-javerts-xref-database.html.