registered_delivery value?

for DLR receipts kannel sets the registered_delivery field  = 1,
looking at the protocol spec v3.4, 5.2.17, this field is more like a bit mask.
I'm not sure if the telcos accurately implement this spec, but one of our telcos
does charge in a premium service for receipts!, so we think we should only
ask for success, or maybe failure as 0x02 bit is where : SMSC Delivery Receipt requested where final delivery outcome is delivery failure.

has setting this field = 1, found by experiment?,  because according to spec,
intermediate notification is 0x10 for example.

can some light be shed on this issue?

thanks