Types of Object Link 
Types of Object Link
You can represent the following types of links between technical objects (pieces of equipment, functional locations):
Definition: One-Way Links
A one-way link is one in which a medium, transferred by means of the link between one object and another, is always supplied in the same direction.
Pump A, Pump B and Pump C are linked with each other by means of water pipes. The water is always pumped from Pump A to Pump B and from Pump B to Pump C. The link is therefore one-way.
Definition: Two-Way Links
A two-way link is one in which a medium, transferred by means of a link between one object and another, is sometimes supplied in one direction and sometimes supplied in the other.
Host A and Host B are connected to each other by a cable. Information flows from both Host A to Host B and from Host B to Host A. This link is therfore two-way.
Definition: Simple Links
A simple link is one in which two objects are connected by means of a single link object.
Pump A and Pump B are linked with each other by means of a pipe. The pipe represents the simple link.
Definition: Parallel Links
A parallel link is one in which two objects are connected by means of several link objects.
Host A and Host B are linked with each other by means of three cables. The cables represent the parallel link.
Definition: Inward Links
Links that lead to a technical object, connecting it with the medium supplied, are described as inward links.
Production Area A is supplied with raw materials from Functional Location Y and Functional Location Z by means of a conveyor belt in each case. The conveyor belts represent the inward links of Production Area A.
Definition: Outward Links
The links that lead from a technical object, transporting the medium to other objects, are described as outward links.
A clarification plant has an inlet pumping station, from which a pump for mechanical cleaning is driven and from which a slope conveyor leads to the waste container. The pump and the conveyor are the outward links of the pumping station.
Definition: Object Networks
An object network consists of several links that share a common characterizing mark. Object networks are formed when different objects are linked with one another.
The water pipes in a large building are summarized in the object networks "Drinking water" and "Central heating".