SeRQL is a RDF/RDFS query language that is currently being developed by Aduna as part of Sesame. It combines the features of other (query) languages (RQL, RDQL, N-Triples, N3) and adds some of its own. Some of SeRQL's most important features are: graph transformation, RDF Schema support, XML Schema datatype support, expressive path expression syntax, optional path matching. The SeRQL query language supports two querying concepts. The first one can be characterized as returning a table of values, or a set of variable-value bindings. The second one returns a true RDF graph, which can be a subgraph of the graph being queried, or a graph containing information that is derived from it. The first type of queries are called "select queries", the second type of queries are called "construct queries".