XPN is relies on a non relational native XML database, where XML documents are stored in a compressed form and indices enables fast access to structure and content, thus enabling a fast evaluation of XQuery queries.
POESIA= Public Opensource Environment for a Safer Internet Access
an opensource Internet content filter (multimodal, mulitlingual) aimed for protection of youth (in schools...); partly funded by the European Commission
CRel is an object relational data store for C programs. Based on a
structure data specification in XML or autogen, it generates code to
store and access the data object. It supports indexing, constraints,
memory management and serialization.