Isearch is an open source software package for indexing and searching
text documents.  It supports full text and field based searching,
relevance ranked results, and Boolean queries, and it can index many
kinds of documents, including HTML, mail folders, list digests, and
text with SGML-style mark up.  Additional document types can be added
as C++ modules.  Isearch also includes CGI tools to provide a web
interface for searching

WWW: http://www.etymon.com/Isearch/

Paul Marquis
pmarquis@pobox.com
