Mark,
in 9.2, a new function was included in HFM known as Phased Submissions.. ie, the ability to Process Manage data by groups of Accounts/Custom Dimensions, not just an all or nothing by Entity as before.
This Setting you have is related to this. A word of warning. In 9.2, this was a 'new' function, so has some "features". It was added following maaaany client requests, now meaning the need for multiple Scenarios is avoided, purely for timing headaches in business cycles.
Contact Hyperion (Oracle) Support, and they will be able to give you the updated documentation.
Good luck