Thanks for that link. I did read the spec, and while the definition itself is clear, the escape clause gives a lot of wiggle room:
I read that as, "the vendor will do whatever it pleases, and you should be grateful to receive a non-negative integer at all." I could be too cynical, though.
Anyway, this particular vendor does other funny things (such as sometimes stripping the q-tag headers from the sampled frame; throttling the frame sampling on the box, but not adjusting the sampling interval in the sFlow exports)
that make it a true joy to work with this gear. ;-)
Cheers,
-- Steven