What significance does a core have on paper?
The core is the center tube where paper is attached during winding. In certain machines a metal or plastic driver is inserted into the core and jogs the paper forward. The inside diameter of the core must be the proper size for the driver to fit through the roll. In other machines the core sits in a cradle and is pulled by friction. Most cores are made of plastic or cardboard material.
Core I.D. - Inside Diameter
Core O.D. - Outside Diameter