The requirements and the product specifications for a system are described in separate instances containing only one component. For example, a system can be an ABS system, cruise control, a control unit or even just a sensor. A system can be assigned a part number (not mandatory).
A system is described as a part type. The specifications for a part type roughly encompass the following areas:

General Product Data 1

Introduction
 

Product Description
 

Function Overview
 

Key Data
 

Product Demarcation
 

Similar Products
 

General Hardware Description
 

General Software Description
 

General Interfaces
 

Failure Management
 

Resource Allocation
 

Calibration
 

Safety
 

Quality
 

Maintenance
 

General Conditions
 

Additional Design Documentation
 

Development Process Specifications
 

Additional specifications
 

General Test Specification
 

Behaviour
 

Architecture

Scheme Diagrams
 

Interface Specification
 

Signal Specification
 

Connection Components Specification
 

Connection Specification
 

Network Specifications
 

Additional Specifications
 

Electrical Characteristics
 
Environmental Characteristics
 
Other Physical Characteristics
 
Construction
 
Human Machine Interface
 
Additional Specifications
 
Parts in Part Type
 

The structure of a system (hierarchical component structure) is described indirectly. To understand this better, there are three terms with which one should be familiar:
Part Type
A part type is a library element which can be used ("instantiated") in a system or higher ranking part type through mounting. A part type has no description of use-related information.
Examples: a control unit, a sensor, an actuator
Part
A part is a mounted part type or a part type in use. It is mounted or employed in a higher ranking system or part type. A part inherits all characteristics of the respective part type. The part itself has a description of use-related information.
Examples: the control unit in an ABS system, the sensor on the left front wheel in the ABS system, the sensor on the right rear wheel in the ABS system
Part Definition
A part definition is a part type with all accessory parts (instances).
Example:
ABS system (part type)  

Control unit (part)
 

Actuator (part)
 

Sensor front left in ABS system (part)
 

Sensor front right in ABS system (part)
 

Sensor rear left in ABS system (part)
 

Sensor rear right in ABS system (part)
 

In this way, a hierarchical component structure is created through successive mounting of part types in the higher ranking system or in higher ranking part types.
The following areas for use-related description are provided for each part of a component. All parameters deviating from the part type (naturally lower requirements than for the part type) can be defined here:

General Hardware

Operating Environment
 

Useful Life
 

Reliability
 

Electrical Characteristics
 

Environmental Characteristics
 

Other Physical Characteristics
 

An ABS system consisting of a control unit, a sensor and an actuator (which itself consists of a cylinder and a valve) would be described by means of a part type ABS, possibly with use-related requirements for the sensor and actuator. Additionally, the sensor and actuator are also specified as part types. This example is illustrated in the following figure:
Figure 2: An example of a component structure