Yes I know, I use the same thing, in fact I bought 200 of each these blue and the pink feeder cards from you back in May.
I am just trying to figure out in a special circumstance where the BP hatchling are together and you would need to identify a individual if it would hurt anything to put a small mark on one with a paint marker. I had seen another breeder doing it on youtube and wanted to make sure it wouldn't hurt the snake and would come off with the shed like they said.