This counts instances where the BAsize, buffer allocation size, field declared in a SIP3 PDU's header turned out not to match the PDU's actual data length, indicating the sender's declared size and the real payload disagree. An admin treats this as a sender-side encapsulation bug, since a well-formed SIP3 implementation always sets BAsize to accurately reflect its payload. For example, a CPE device with a buggy SMDS stack that miscalculates padding could consistently produce PDUs with mismatched BAsize values, showing up here as a steady trickle of increments rather than a one-off blip.