The read rate of a cell-ID direct part mark (DPM) is a probability defined at a single read point, but the line experiences it raised to the power of the number of read points each cell passes. Assuming 12 read points and 22,000 cells per shift, a 99.5% read rate generates 1,320 No-Read exceptions per shift, while 99.95% generates 132. Under the same assumptions, OEE falls from a baseline of 84.64% to 75.50% at 99.5% (−9.14 pp), but only to 84.13% at 99.95% (−0.51 pp). A DPM specification should therefore be defined not as "read rate X%" but by three items: verification grade immediately after marking (ISO/IEC 29158), allowable exceptions…