In Equipment Leases there is the concurrent request Transfer Normalized Equipment Lines to GL which

In Equipment Leases there is the concurrent request Transfer Normalized Equipment Lines to GL which has a parameter 'Derive GL Date'. This has options of 'Due Date' or 'Period Name'. However if my stream date is in an open past period regardless of which option I chose the date I get is still the first day of the current period when I want it to be the last day of the open period in which the stream date falls. What is the intended functionality behind this parameter?