Qualification of a reticle is a very important step for a mask shop. For defect inspection, automatic die to die inspection can detect the random defects and the die to database inspection system can detect the missing patterns as well as the pattern placement of the reticle. When die size becomes larger, and the field size of the stepper lens is limited,it is a common practice that only one die is placed on a reticle.
Parkson W Chen,
"Alternative to die-to-database mask inspection", Proc. SPIE 1604, 11th Annual BACUS Symposium on Photomask Technology, (1 January 1992); doi: 10.1117/12.56941; https://doi.org/10.1117/12.56941