Abstract: A marking system for a textile web in production comprises a heat-, water-, and chemical-resistant substrate layer having a front and back face, pigment forming indicia carried on the front face of the layer, and a heat-, water-, and chemical-resistant cover layer formed of a transparent and flexible synthetic resin and embedding the substrate layer and pigment at least over the front face thereof. The cover layer is bonded to the web. The cover layer secures the indicia on the substrate layer and the latter on the web. The pigment is printed on the front face of the substrate which itself is made of glass fibers. The substrate layer is provided on its rear face with a layer bonding it to the web. The bonding layer in turn can be an adhesive, or can be of the same water-, chemical-, and heat-resistant material as the cover layer.