Major revision

In this version a lot has changed. For the end-user, the most important changes are:

• Ability to search for concepts by searching the names and synonyms of source concepts that map to standard concepts in the vocabulary. For example. the term 'Paracetamol' is not a name or synonym of the standard concept for Acetaminophen, even though it means the same thing. However, there are source codes with the name Paracetamol that are mapped to the Acetaminophen concepts, so we can find it that way if our source code system only refers to Paracetamol.
• Ability to investigate the context of a concept. At various places Usagi now reports the number of parents and children a concept has, which will help identify orphan concepts that are not integrated in the hierarchy. The Concept information panel provides detailed information on the parents and children, as well as source concepts that map to a concept.

On the back-end, Usagi now uses a Berkeley database to store information on concepts and their relationships. Also, Athena files are now read through a dedicated reader, which should reduce the number of read errors.