The CTTN-system is a computer program which provides advanced processing or temporal notions. The basic data structures of the CTTN-system are time points, crisp and fuzzy time intervals, labelled partitionings of the time line, durations, and calendar systems. The labelled partitionings are used to model periodic temporal notions, quite regular ones like years, months etc., partially regular ones like timetables, but also very irregular ones like, for example, dates of a conference series. These data structures can be used in the temporal specification language GeTS (GeoTemporal Specifications). GeTS is a functional specification and programming language with a number of built-in constructs for specifying customized temporal notions. CTTN is implemented as a Web server and as a C++ library. This paper gives a short overview over the current state of the system and its components. Category C