The #WF_REASSIGN_LOV attribute must be of type role and must have a source of Send. You can either specify a particular role as a constant value for the #WF_REASSIGN_LOV attribute, or specify an item type attribute as the value and include logic in your workflow process that dynamically sets that item type attribute to the role you want at runtime. If no existing role meets your needs, you can include logic in your process to create an ad hoc role at runtime and add the users you want to that role. See: CreateAdHocRole, Oracle Workflow API Referenceand AddUsersToAdHocRole, Oracle Workflow API Reference.
Source: http://download.oracle.com/docs/cd/B14099_19/integrate.1012/b12161/defcom26.htm
