its 1/8 of an inch all around. its necessary thing for printing presses. as they can shift side to side. although modern presses are pretty good i hear.
i know they cut stuff out but...in your case i would try to make all the art in the save area so that outsite it will just cut white. right now it would cut trough your panels. at the end its how the panciler prepared the page but you should talk with him about such stuff
right now it would cut trough your panels. at the end its how the panciler prepared the page but you should talk with him about such stuff