The efficient and sophisticated representation of the structure of the documents being circulated over the Internet allows for effective querying and reasoning over them. This is a major goal for large information resources like the World Wide Web (WWW). Constraints are a valuable tool for managing information. In this work, we consider how constraint-based technology can be used to query and reason about semistructured data represented using the constraint-logic implied representation models. The constraint system, FT£ , provides information-ordering constraints interpreted over feature trees. Based on this approach, we show how a generalization of FT£ combined with path constraints can be used to formally represent and state constraints and reason over semistructured data. The proposed query language is extended to facilitate query relaxation when the exact solution to the query cannot be obtained from the data repository. The applicability of the above framework, proposed for semistructured data, is examined for a particular case regarding XML documents circulated and stored over the Web.