Seems we crossed posts, Alan!
I believe this is a class of blades distinct from the coastal Melayu beladau: the latter tend to have blades with a broader base (approaching their Arab in-laws
).
Usually beladau blades are also more strongly curved while the central Sumatran highland daggers NN03 tend to exhibit a slightly curved blade only; Leif's example shows the strongest curve I've seen so far (with most of the curve located at the base though).
Regards,
Kai