Abstract: The belt of a belt conveyor has at least one layer provided with windows which extend all the way through the layer and have outlines corresponding to those of letters, numerals and/or other symbols. The windows receive inserts or indicia which preferably fill the respective windows and are welded, glued or otherwise affixed to the belt. The useful life of the inserts is the same as that of the belt, and at least one characteristic (for example, color) of each insert is selected in such a way that the installed insert or inserts can be readily discerned by an eye at one or both sides of the layer. The layer which is provided with the window or windows can have one or more strata (thinner layers), such as an outer stratum of plastic material, a reinforcing intermediate layer or stratum of textile material or the like, and a layer or stratum which can constitute a substrate.