How Connection in Enterprise Journals Target Properties works?

Could somebody help me to understand how "connection" field in target setting works?

While creating a target in enterprise journals, there is "connection" field which is enabled when a user selects direct integration flag on. An user can select applications from dropdown list. In my case, there are Account Reconciliation and Planning. I am wondering what is the difference between choosing AR and Planning for connection field. As far as I understand, the target is handling data export to ERP or other systems and not to do with incoming data such as journal from AR. If so, selecting AR in connection field makes no sense since it is supposed to only feed