In the discussion of 'OO'(76:1) scale relative to 'HO' (87:1)scale, 'TT'(120:1) was brought up. In order to focus on that scale, without confusing matters from the other discussion, I opened this thread to explain the what , and why of the goings on in 'TT' scale.
It antedates 'N' (1:160)...