Additional relationships are introduced between the elements listed above. These are realized as references. The following table contains a listing of all types of references to be considered in this context and includes those already in existence.

Types of references
No.
Designation
Source element
Target element
Meaning
1
<system-ref>
<requirements>, <product-spec>
<part-type>
Defines the top-level part type (exactly one) for each of the two views.
2
<part-type-ref>
<part>
<part-type>
Assigns the specific part type (exactly one) to a part.
3
<sw-function-ref>
<software>
<sw-function>
Allocates software functions to the software of a part type ( none, one or several), that are described within the software of another part type, e.g. multiple use of such functions as operating system or network management functions.
4
<sw-function-ref>
<sw-function>
<sw-function>
Allocates software functions to a software function (none, one or several) within the same software description, that constitute the decomposition of the first.
5
<fulfills-ref>
Part, SW function
Function
Allocates those (behavioral) functions to a part or a software function (none, one or several) that it realizes.
6
<function-view-ref>
Function
Function
Allocates the (behavioral) function in the view requirement, to a specified (behavioral) function in the view consent, that is realized by the first.
The following diagram illustrates the types of references as an example (no. 6 excepted).
Figure 21: Extended structure with references