Well, I bought this shifters (Shimano XTR SL-M952) and during the cleaning I found this curious detail in the rear shifter body (integrated to the clamp). What is the purpose or function of this thing?
There was a remote shifter available for ST-M952 and SL-M952 and some others of the era, so you could shift from your bar end. It actuated the main shifter via cables and housings. This is a stop for the housing.