Screen image of OReFiL. This image shows the search result of the query protein protein interaction. MeSH terms annotated to the MEDLINE abstracts in the hit list and their conceptual ancestors in the MeSH hierarchy are displayed in the alphabetical order in the MeSH term box (encircled by a dotted line), and each font size reflects the frequency. MeSH terms also can be used to filter the result by narrowing down to those entries that have a specified MeSH term. Changing a query to narrow down is done by clicking a MeSH term in the box. Clicking a same MeSH term twice removes it from the query.