SPWorkflowModification Class
Represents a workflow modification.
Namespace:
Microsoft.SharePoint.Workflow
Assembly: Microsoft.SharePoint (in Microsoft.SharePoint.dll)
Available in Sandboxed Solutions: Yes
Available in SharePoint Online
You may want to enable your users to alter the workflow at certain points while it is running on an item. For example, you might want to enable a user to assign his or her task to another person or even add a specific task to the workflow. The options you present to users to change the workflow as it is running on an item are called modifications.
For more information on workflow modifications and modification forms, see Workflow Modification Forms (SharePoint Foundation) and EnableWorkflowModification.