I am a bit confused. I am aware that BPC is used (as described in RawPedia)
If you want to adjust an image for printing and you have an ICC profile for your printer-paper combination you could set that as your output profile, enable “Black point compensation” so that the blackest black in your image will match the blackest black your printer-paper combination is capable of reproducing,
However I would have thought that use of the printer’s ICC profile for soft proofing would inherently specify the required compensation, particularly when I leave the image in that profile when sending it to the printer. That, I assume, is how the print shop would “know” BCP has been incorporated in my proof. Without access to my monitor how would the printer know what BPC to use? What is additionally accomplished by checking BPC in the ICM panel for soft-proofing?