LT XML is an integrated set of XML tools and a developers' tool-kit,
including a C-based API.

The LT XML tool-kit includes stand-alone tools for a wide range of
processing of well-formed XML documents, including searching and
extracting, down-translation (e.g. report generation, formatting),
tokenising and sorting.

Sequences of tool applications can be pipelined together to achieve
complex results.

For special purposes beyond what the pre-constructed tools can
achieve, extending their functionality and/or creating new tools
is easy using the LT XML API. Minimal applications require less
than one-half page of C code to express.

LT XML provides two views of an XML file; one as a flat stream of
markup elements and text; a second as a sequence of tree-structured
XML elements.  The two views can be mixed, allowing great flexibility
in the manipulation of XML documents. It also includes a powerful,
yet simple, querying language, which allows the user to quickly and
easily select those parts of an XML document which are of interest.

WWW: http://www.ltg.ed.ac.uk/software/ltxml/