The NITE XML Toolkit (NXT) is open source software for working with language corpora, with particular strengths for multimodal and heavily cross-annotated data sets. In NXT, annotations are described by types and attribute value pairs, and can relate to signal via start and end times, to representations of the external environment, and to each other via either an arbitrary graph structure or a multi-rooted tree structure characterized by both temporal and structural orderings. Simple queries in NXT express variable bindings for n-tuples of objects, optionally constrained by type, and give a set of conditions on the n-tuples combined with boolean operators. The defined operators for the condition tests allow full access to the timing and structural properties of the data model. A complex query facility passes variable bindings from one query to another for filtering, returning a tree structure. In addition to describing NXTȁ9s core data handling and search capabilities, we explain the stand-off XML data storage format that it employs and illustrate its use with examples from an early adopter of the technology.