What's the proper first letter designator for a torque guard in a DIN or ISO compliant P&ID? I find fist-letter designators for a few physical values (L for level, S for speed etc.) but none for force or torque. As of now I'd use WS+ (W for weight, mass) as the closest but I'm not entirely happy.
This is either non defined in the codes or nobody bothered to copy the designator to where I can find it.
Note: I'm fine with an answer of the type: "I did X, a dozen people looked at my drawings, no one was confused"