Reason for cutout in top of Ruger box

[67stingray]

Does anyone know why there's a cut in the top of some of the yellow and black boxes used between 1979 and 1994? The majority of the ones I've seen have been used as return boxes for old model single-action conversions with a stamp indicating original parts being inside, but I have an early MK-6 that has the cut. Here's a picture of it.
Bennett

[rugerguy]

why we may never know, but I've seen that and noted it years ago was told it was a "mistake" from the vendor and the old man never threw out anything, so used them for that purpose ( returns) as well as some other boxes of different colors such as brown, with metal corners like the blue/silver S&W two piece boxes as well as brown, one-piece fold up boxes with a Ruger logo in black on the top of the lid,

[67stingray]

Thanks for the response Dan, your reasoning for it makes as much sense to me as anything else I could figure.
Bennett