What is a BC01-R

[Chris Zach via cctalk]

Quick question: I'm going through my old cables looking for the paddle 
interface for the Current loop for my pdp8/L. I thought I saved one from 
my old pdp8/I, maybe not.

Regardless, I found a M857 board with a RS232 cable on it and BC01R-25 
on it. Was that for a pdp11/05 by chance?

Oddly enough I also found the interface adapter that goes into my VT52 
to support 20ma current loop devices. I currently use the VT52 as an 
RS232 console for my pdp11, but still, Wow.