Definition of Binding 
At definition time you create binding definitions for the workflow. This involves specifying the assignment rules for how data is exchanged between two containers. At runtime these binding definitions are executed making workflow execution possible.
Note
If a target container from a source container element is to be filled with a binding at runtime and if the source container element is initial or unavailable, then determine in the options of the binding instruction whether the content of the target container element is changed by the binding.
You can also allocate values to container elements using initial value assignment at definition time.
Example
Application
Within the transaction for creating an accounting document (object type AccountingDocument), an event is generated created), which indicates that a document has been successfully created. This event is to be the triggering event of a workflow.
Event
The event container is passed with this event. This container always contains an element _Evt_Object with a reference to the object created.
Workflow container
In the container of the workflow that is to be started by the event created of the object type AccountingDocument, you have created a mandatory import element (under the ID AccountingDocument for example) with a data type reference to the object type AccountingDocument. The element can therefore hold the reference to the object created (type AccountingDocument) at runtime.
Binding to workflow
The event parameter (= element in event container) _Evt_Object can be passed in a binding to the workflow container of the workflow that is to be started in response to the event. You define the following binding for this:
_Evt_Object (event container)
AccountingDocument (workflow container)
The graphic below illustrates which bindings can be defined.

You define the bindings from the task container in the following two places:
There are binding definitions to the:
Method container (for import parameters of method)
Rule container (for definition of default rules)
The binding definition to the workflow container.
You define the bindings from the workflow container within the Workflow Builder. There are binding definitions to the:
Task container (activity, user decision, document from template, send mail, form step)
Event container (event creator)
Rule container (for definition of responsible agents and recipients)
You define the binding from the method container to the task container (for export parameters of the method with synchronous methods) during definition of a task.
You make the binding definition from the rule container to the workflow container during the definition of a step.
You define the bindings from the event container in the following three places:
In the definition of a task for the binding definition to the task container (for triggering or terminating events of the task).
In the Workflow Builder in the basic data of a workflow for the binding definition to the workflow container (for triggering events of the workflow).
In the Workflow Builder in the definition of a wait step for the binding definition to the workflow container.
Note
The system makes proposals automatically for the binding definition between the workflow container and the task container. You can change these proposals. For information, see Rule-Based Proposal for Binding Definitions.
You define the bindings in the binding editor, which is always called via a definition tool. This cannot be done separately.