Thank you, Piotr. I've already implemented the request options since it's the only way I know that can get the info out.
Back to TREAD_BMATS, from the ref. guide (please see the attachment) there's a part with "... of selected (current) tread ..." that throw me off. It kinda suggests that you can apply the label with specific tread (tab-select). Maybe it's just a typo, a copy and paste mistake in the ref. guide.
Even with the stair selected (not tread), text2, 0, 0, tread_bmats doesn't crashed but gives off 0 (zero) which I don't think it's correct.
It's even more ... I would say "surprised" ... that ArchiCad also crashed when the label is applied to a tread with nothing but the following code in 2D
if glob_elem_type = 21 then ! Stairs
text2, 0, 0, "stairs"
text2 0, 1, tread_bmats
text2 0, 0, "not stairs"
With this "if-then", the "tread_bmats" shouldn't even run when a tread is selected because glob_elem_type for tread is 22. But ArchiCad crashes anyway.
Maybe I should stay off "trade_bmats" for now.