This read-only PerfTotalCount reports the count of frames truncated because the DSL receiver overran and had to cut a frame short, scoped to the DSL port's current, still-accumulating measurement period (not yet rolled into the interval history). Operationally, truncated frames are lost data, and a rising count suggests the receiver is being overwhelmed faster than it can process incoming bits. For example, watching this counter tick upward in real time during a support call lets an admin confirm a truncation problem is actively happening right now, not just something that happened earlier today.