Developed by DongWook Shin, a professor of Computer Engineering at Chungnam National University, Republic of Korea, who spent a sabbatical at the US National Library of Medicine and also developed BUS.
Warning: this product has no indication of continuing development.as of October, 2001
For other options, see the XML Search Engines Listing.
XRS is an index and search engine that recognizes SGML and XML file structures and hierarchies, based on his BUS (Bottom-Up Search) technology. It creates relatively small indexes (30-50% of the original document set size). There are options for Boolean and Vector search, DTD structure, element counting, and so on.