A web structure with electromagnetic radiation shifting indicia is disclosed. The indicia provide signals used in controlling various processes to be performed on the web as well as for controlling movement of the web. The preferred indicia are normally essentially invisible so that the physical appearance of the web is not affected. The indicia emit wave-shifted electromagnetic radiation in response to incident radiation of a given range to provide a means for determining the positioning of the web during movement as the processes are performed. Process and apparatus for making and using such webs are also disclosed.
