When you go to the Appendix D in Oracle Text Reference they provide lists of stopwords used by Oracle Text when indexing table contents.
When I see the English list, nothing puzzles me. But the reason why the French list includes moyennant (French for in view of which) for example is unclear. Oracle has probably thought it through more than once before including it.
How would you constitute a list of appropriate stopwords if you were to design an indexer?