Primarily in the analysis OMT notation is used to define the functional model and the object structures of the intermediate states. In the functional model an ellipse is a process, an arrow is a data flow and a data store is represented by two thick lines, one above and one under, surrounding the data store name. In an object structure a square or rectangle is a class, a class is a prototype data structure which when instantiated becomes an object. Lines between classes represents relations. A single line represents a unary relation between instanses of the classes. A filled circle represents relation with zero or many instanses, while an open circle represents a zero or one relation. A +1 represent a one or many relation.
ITS Uppsala university