OTB = Over the Board
CoT OTB?

What does this mean
Cost is Circle of Trust.
It's a group that plays Daily chess just like OTB, with none of the allowed resources.

When Martin said "Cost is Circle of Trust" what he meant was "CoT stands for Circle of Trust".
"CoT OTB" is a group on Chess.com that plays Daily Chess just like OTB. without Opening Explorer and Analysis Board (moving pieces and saving analysis). It's called Circle of Trust, because everyone agrees to trust the others in the group that they are NOT using Opening Explorer and Analysis Board.
What does this mean