CONFIDENTIALSLM 1 204. RANGE - MARK: A phrase which when used by the Approach Officer during a periscope observation directs the Periscope Assistant to read the stadimeter or telemeter range and informs the Fire Control Party of the time of the range. When spoken by the Radar Operator it indicates that the radar is on the target and the range repeaters are reading correctly. It is usually paralleled by a buzzer and a mark light in the latter case.
I believe this demonstrates that the TBT/scope were not connected to the TDC. It was all done via voice and visual readings.
The rest of this found below and a great read:
http://hnsa.org/doc/attack/