it turns out there's an error in the KY11-LB
drawings.
...
I have 'fixed' a copy of that page from the print set, and will (soon)
issue an updated PDF.
OK, I finally got a round tuit; new version here:
http://ana-3.lcs.mit.edu/~jnc/tech/pdp11/MP00015_KY11-LB_Jan78.pdf
(same place as the old version, now deprecated).
Noel