When I first started stitching Japanese embroidery, my fingers were not as sensitive like they are now. I couldn't tell one side of the protective tissue or finishing paper from the other (unless I could see the sheen on the underside.) Even then I didn't always remember if the sheen side should be up or down.
With the sheets you receive, they are marked to distinguish one from the other but, more importantly, to indicate which side should be facing up when placed over your stitching. In other words, if you can read the wording when it is down, you have the correct side toward your needlework. Ohhhhh so easy and so reassuring!