After all these years of working with the system, I just realized that the Transactions by Period report cannot be filtered using subaccount segments. The report currently uses the full Subaccount CD for filtering and it does not appear possible to filter based on a specific segment.
We have clients that are requesting detailed GL balance reports for a range of accounts by subaccount segment (i.e. Department) where the department code is in the third segment in the hierarchy. The current structure of this report cannot be supported in this way.
An alterative is expand the ARM row sets to provide transaction level data.