What is Application Integrations in Project Costing Set Up?

Do you know what is Application Integrations in Project Costing Set Up?

It has the following list and these condition is the following:

Oracle Fusion Payable : enabled●

Oracle Fusion Expenses:disabled

Oracle Fusion Purchasing : enabled●

Oracle Fusion Inventory Management:disabled

Oracle Fusion Receinving : enabled●

Oracle Fusion Third-Party Applications:disabled

None : enabled●

But I can import cost from Third-Party Applications with Project Transaction Source even though it is disabled, and I can transfer cost from Inventory and see information of order etc. even though it is disabled too.

If you know affect for using Application Integrations, please let me know.

Thanks,