I don't have an answer to your question, but since you are specificly asking about classes in the Lucene-Java API I would suggest you re-post your question to the java-user@lucene. the general@lucene list is for broader discussions about the entire lucene project (and all subprojects) or when people have extremely general questions aren't aren't sure where to start (ie: use Solr vs use Nutch, vs use PyLucene, etc...) -Hoss