A special kind of Situation that allows to include time indexing for the classifies relation in situations. For example, if a Situation s 'my old cradle is used in these days as a flower pot' isSettingFor the entity 'my old cradle' and the TimeIntervals '8June2007' and '10June2007', and we know that s satisfies a functional Description for aesthetic objects, which defines the Concepts 'flower pot' and 'flower', then we also need to know what concept classifies 'my old cradle' at what time. In order to solve this issue, we need to create a sub-situation s' for the classification time: 'my old cradle is a flower pot in 8June2007'. Such sub-situation s' isPartOf s.