 Where accurate translation of syntaxes is possible, systems using different syntaxes may also interoperate accurately.In some cases, the ability to accurately translate information among systems using different syntaxes may be limited to one direction, when the formalisms used have different levels of "expressivity" (ability to express information).A single ontology containing representations of every term used in every application is generally considered impossible, because of the rapid creation of new terms or assignments of new meanings to old terms.