The new I/O License Demand dialog in DeltaV Explorer (v12) enumerates these very well.
http://www3.emersonprocess.com/systems/support/bol1231/c_io_licensing.html
Prior to v12, this is still easy using the system licensing report. (DeltaV Explorer -->File--Licensing-->Licensing Report.)
Under the Node:System:Assigned License Features: you'll see the # Configured count of each mentioned I/O type.
I'm not looking at a system with FF installed, but I think in either case, the FF Dsts are counted in the AO/AI/DO/DI categories based on the higest functional level function block reference (1 dst per device prior to v12, and 1 dst per device with up to 16 references in v12)
v12 http://www3.emersonprocess.com/systems/support/bol1231/c_fieldbus_license_guidelines.html
v11 http://www3.emersonprocess.com/systems/support/bol1131/source/extfile/b_theory/html/dsts_and_scada.htm