I was looking in the brake bleeding area of the W123 Chassis FSM and there was this notation: "Attention!
The 4 piston fixed Caliper, Installed in September of 1985, has one vent screw inside and one vent screw outside. For venting the brake system or replacing the fluid, remove the front wheels so that the outer pressure chamber can be vented."

Is that The 4 piston fixed Caliper part of the Cars equipped with the ABS system or is it an error in the Manual? Or what?

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84 300D, 82 Volvo 244Gl Diesel