You won't find it in the NEC really. More of a listing issue.
Yes, this is allowed if the instructions on, or with the panel are followed for the use of the approved breaker hold-down device.
Usually a plastic clip, or metal screw that holds the breaker in. Often you'll find the 'hold-down kit' part number on the sticker, not far from the 'ground bar' part number or other acessories. And on the circuit diagram it will show where it can be placed.
