EHRI/ehri-ead-preprocessing — pull request #2 by mikesname (2014-08-29 11:50:14+00:00)
Title: Add a transformer for changing absolute IDs into relative ones

As per discussion on Trello [here](https://trello.com/c/c4QCgKOb/14-convert-absolute-unitid-values-to-relative-ones).

Overall I think this makes the resulting XML more normalized and generally nicer-looking. **NB: Could probably use more testing with real-life files...**