Models may also be categorized by place of service, for example, US or Soviet. They may also be categorized by function, for example, combat engineering vehicles, recovery vehicles, etc. In all cases, the national and unit markings on the replica determine the era and user nationality. For example, a model of a Sherman tank, a World War II design, would be considered a 'modern' model if the tank were shown in Israeli markings from the Six-Day War. The same vehicle in World War II US Army markings would be considered a World War II Allied subject.