From the driver's seat. A tugger runs the aisle with the driver's eyes about 1.5 m off the floor and the sign 6–9 m up on a truss chord, so the driver reads it from 8–12 m out at 30–40° above the horizon. The face tilts down to meet that line of sight instead of being seen edge-on; the code is set at the largest cap height the width allows (about 40 mm for six characters on a 240 mm plate — readable at 15 m); the Code 128 gets bars up to 2.2 mm wide and 50 mm tall, set flush into a matte face so an extended-range imager reads it from 10 m and more. Mounting: a flange along the top edge with four slots takes zip ties round a chord or #10 screws into a beam; the flange sets the tilt, so every sign in the aisle hangs the same. Two halves flange to flange make a two-sided sign for a cross-aisle. Modular: the frame carries two rails; character tiles (0–9, A–Z, dash) and a barcode tile slide in and an end clip locks them, so a re-slotted bay gets a new tile pack, not a new sign. Every sign prints flat, no supports, on one P1S plate.