Pieter,
The reason for the binding is to make it easier to use while treating fish out by the pond. Call it a field manual if you will.
As for the metric measurements... I'm doing a Dutch translation (sorry no Afrikans

)at the moment with metrics only. I hope to transplant the relevant bits to the English version so Dunc will have a metric version in English for the non-US/UK community.
Should be ready to send back to Dunc in a couple of months.
B.Scott