Amberfish is general purpose text retrieval software, developed at Etymon
by Nassib Nassar and distributed as open source software under the terms
of version 2 of the GNU General Public License (GPL). Its distinguishing
features are indexing/search of semi-structured text (i.e. both free tex
and multiply nested fields), built-in support for XML documents using the
Xerces library, structured queries allowing generalized field/tag paths,
hierarchical result sets (XML only), automatic searching across multiple
databases (allowing modular indexing), TREC format results, efficient
indexing, and relatively low memory requirements during indexing (and the
ability to index documents larger than available memory). Z39.50 support
is available. Other features include Boolean queries, right truncation,
phrase searching, relevance ranking, support for multiple documents per
file, incremental indexing, and easy integration with other UNIX tools,
The architecture is also designed to permit proximity queries; however,
they are not fully implemented at present.

WWW: http://www.etymon.com/tr.html

This port also includes the Porter stemming algorithm for suffix
stripping, available at:
     http://www.tartarus.org/~martin/PorterStemmer