Direction of Bamboo Limb Pieces

[KenH]

I've been looking at the piece that Stephen posted here years ago about the Ming era non-repeating crossbow:
http://www.atarn.net/images/ming_xbow/ming_xbow.htm

and also discussions of Bhutanese bamboo bow construction.

All along I'd been assuming that, like modern bamboo-backed bows, the outer surface of the bamboo was towards the back -- both for the Bhutanese bows and the Ming "leaf spring" prod segments.

However, it seems the Bhutanese use the inner surface of the split culms as the BACK of the bow, and the exterior surface as the BELLY.

Did the Bhutanese know something that the Chinese didn't? Enquiring minds want to know... Can someone who reads Chinese tell me -- did that Ming crossbow have the exterior of the culm facing the back or the belly of the prod?