What is the Texis relevance ranking algorithm? Is it tunable?

Texis contains a sophisticated ranking system that may be tuned in various ways. Factors it uses include: closeness of query words to the beginning of a document; order of occurrence of the query words; and proximity (closeness) of query words to each other within a record. These factors may be weighted to change the ranking behavior. As an example of how that might be useful: newspaper articles tend to have the most important material close to the beginning, so in a newspaper search application, you might give that factor more weight.