Using Expressions in Binding Definitions 
Using Expressions in Binding Definitions
Use
You use an expression to assign a value to a container element in the binding definition.
Features
Expressions must be assigned using the F4 input help. You have the following options for assigning values:
Constant
Fixed value or fixed object reference, which is assigned to a container element at runtime.
Container
Direct assignment of a container element or assignment using a container element from the source container.
The variable is created in the form
The variable is specified in the form
This indirect establishment of values can also have two or more levels. The variable then appears in the form
&<ObjectReference>.<ObjectReference>.<…>.<AttributeName>&.The variable is specified in the form
System field
Field in table
SYST .The variable is specified in the form
%<SystemFieldName>% . Depending on the environment, not all the expression components named are always offered.Activities
Use the F4 input help when making assignments. Bear in mind the color legend. The colors indicate whether an assignment is permitted as far as the data types of the two partners are concerned, and whether the assignment may be defined. As an alternative to the "technical" element ID, you can display the name of the container element by choosing 
.
Activity
Choose between constant, container and system field to specify the type of expression. If you specify the expression as the target of a binding definition, you can only choose container.
Entries can occur twice when container elements are displayed, the second entry having an addition.
Addition "with index"
The addition "with index" only appears for a multiline container element if:
If this entry is chosen, only one line of the multiline container element is assigned to the single-line target element in the binding. For further information, refer to
Binding Definitions from Source Container to Target Container.
This application should only be used within dynamic parallel processing.
Addition "add instead of change"
The addition "add instead of change" only appears for a multiline container element, if the container element is a target element of a binding definition.
This addition means that the value of the source element is appended to the content (if any) of the target element. For further information, refer to
Binding Definitions from Target Container to Source Container.