German to English Tech/Engineering Materials (Plastics, Ceramics, etc.)

Hello, I'm trying to interpret the significance of "rd." in the measurement found in the following sentence:

"Der Bruch geht von einer deutlich ausgeprägten Kaltlaufstelle aus (0 rd. 1,5mm), die bis zur Bauteiloberfläche reicht."

Sentence something like: "The fracture runs from a significantly pronounced patch of cold lap (0 rd. 1,5mm) reaching as far as the piece's surface."

I think we're talking micrometers here; does "rd." indicate a estimate i.e. "about" or "around" 1,5mm?

Thanks!