The ancestry relationships found in provenance form a directed graph. Many provenance queries require traversal of this graph. The data and query models for provenance should directly and naturally address this graph-centric nature of provenance. To that end, we set out the requirements for a provenance data and query model and discuss why the common solutions (relational, XML, RDF) fall short. A semistructured data model is more suited for handling provenance. We propose a query model based on the Lorel query language, and briefly describe how our query language PQL extends Lorel.Engineering and Applied Science
