[Exist-open] Bottom-up XPath processors?

[David M. <ma...@ee...>]

Hi all,

I noticed that Wolfgang mentions in "eXist: An Open Source Native XML
Database" that "most [XPath] implementations available as Open Source
software rely on conventional top-down or bottom-up tree traversals to
evaluate path expressions."

I'm familiar with several top-down XPath implementations (Xalan, Jaxen,
JXPath), but what are some bottom-up ones?

Thanks very much.

djm