This International Standard defines a formal language for accessing information organized according to the Topic Maps paradigm. This document specifies syntactic rules to form valid query expressions to extract information from a Topic Maps instance and also provides an informal and a formal semantics for every syntactic form.

To constrain the interaction and information flow between a querying application and a TMQL query processor (short: processor) this International Standard also describes an abstract processing environment, loosely defines the passing of parameters into the query process and the exchange of result values. This environment also includes a minimal, predefined set of functions and operators every conformant processor must provide.

This International Standard does not define an API (application programming interface) to interact with query processors and also refrains from naming certain error conditions. It also remains silent on other implementation issues, such as optimization or error recovery.