To understand the ontology based concepts of DeepaMehta it is very important to understand the type-instance distinction that separates an abstract concept (types) from the objects which are particular instances of the concept (topic). For example, the particular bicycle in your garage is an instance of the type of thing known as "The bicycle". Types of obejcts or things can be sets, collections, classes or kinds of things. Instances of a type are the concrete basic or "ground level" obejct. Here are some examples:

• TopicType?: Fruit => Instances: Banana, Appel, Cherry, ...
• TopicType?: Name => Instances: Andi, Christina, David, Sandra, ...
• TopicType?: Flower => Instances: rose, tulip, sunflower, ...

In DeepaMehta every Topic is an in instance of a specific TopicType?.