An example of a later larger-scale system aimed at practical goals was BBN's JANUS system (Ayuso et al. 1990). This was intended for naval battle management applications, and could answer questions about the locations, readiness, speed and other attributes of ships, allowing for change with the passage of time. It mapped English queries to a very expressive initial representation language with an “intension” operator to relate formulas to times and possible worlds, and this was in turn mapped into the NIKL description logic, which proved adequate for the majority of inferences needed for the targeted kinds of QA.