Hi Mark,

thanks for your post. The terminology is a bit mystifying for sure. With the two folks I've been having this discussion with so far, I know that each of them is fairly familiar with the terms I'm using - but not the general audience. I think another thread as a glossary isn't a bad idea.
I have an article coming out in the next TFG Journal, where some of the terms for the various components in a frame will be explicated.
Until then, here's a rundown:

keta: the wall plate/building perimeter beam. Also the name for the beam used along the veranda to support the decorative rafters - called the 'noki-geta'. If it's a round log, it's often termed a 'gagyo'

hari: tranverse beams that run across from wall plate to opposing wall plate (keta to keta). There are different types of these, and if the word 'hari' forms a suffix, it becomes '-bari', as in 'koya-bari-gumi' (hut beam construction)

taiko: the name for a hari that has been slabbed on two sides.

mizu-zumi: lit. 'water-ink'; the horizontal reference line established on timbers at a pre-determined height

I think that covers the terms used so far. If you are not clear on the meaning any of these terms, or any other Japanese carpentry words that you may have come across, please let me know.

Chris