Integration of spatio-temporal data in Databases: Design of a schema editor for MurMur

data types (ADTs) provide MADS with the predefined spatial and temporal constructs. These ADTs consist of data structures and sets of operations. They are used for describing the spatial and temporal extents of the schema elements. Each ADT has an associated icon, to be used in schema diagrams. Spatial ADTs define the spatial extent of the described feature. The MADS predefined SADTs are: point, line, oriented line, simple area, simple geo, point set, line set, oriented line set, complex area, complex geo, and geo. No support is provided for 3D, but corresponding SADTs will be added when MADS is extended. However, the design principle allow database designers to define their own SADTs, as required by their applications. Predefined operations are associated with each SADT, such as length for line, or surface for area. The SADTs’ structure and icons are shown in Figure 3.1. The point SADT is used to represent features materialised by a single point. A line is a mono-dimensional set of connected points defined by one or more linear (in)equations. Thus are included curves, polylines, and open or closed lines. An oriented line is a line with the notion of start point and end point. A simple area is a two-dimensional set of connected points that lie inside a boundary formed by one or more disjoint closed lines. If