​I remember those, but I do not have a manual for it.

I reasonable guess is they tried to clone the VT-100 which means its ANSI sequences but not full ANSI and lots of strangeness - Thank you to my old friend Tom Kent who had a lot to do with the original FW and the keyboard. In his defense, the ANSI sequences were not yet a standard when then started that project.   So they took what they knew was going to be there, add a ton of DEC specific stuff and the result is history.

BTW: If you even wanted to know why the original Masscomp keyboard worked as it did, was because Tom had the "second systems effect" when he did the MC-500  and I always tease him about it all the time - although unlike the MC-500 you could not use the VT-100 as a weapon ;-)​

Anyway - I just looked in the original VT-100 programmer guide again and could not find the sequence "\033c" defined in it.  So I'm >>guessing<< Tom and team did not implement it, and thus c.itoh did not either when they cloned it.