Thanks for the link, Malcom. I started into that thread, or one like it, a couple of years ago then got sidetracked. I'm slogging through it now, as I remember my peripheral part of the investigation as if it were last month.
I have quite a lot of technical info to write that I don't believe has been covered in these forums, and it should be interesting to those involved. I just don't want to repeat seemingly common knowledge, or get facts wrong.
Yes, it regards Douglas, Collins and Litton, the players in the AINS-70, Area Inertial Navigation System, the forerunner of the ubiquitous FMS.
GB