1. The film is composed of a transparent film and a black drug film. The black content on the film is the drug film. The drug film is arranged and attached to the film according to the content to be printed to become the film. 2. Film is divided into upper film and under film, which are suitable for printing machines with different principles. This needs to be known. For example, our rotary rotary machine needs to produce the lower film, while the flat label machine needs to produce the upper film. If there is an error, the printed content will be incorrect. 3. Distinguish the top and bottom of the film. The method is as follows: First, we need to hold the output film in our hands, and the content we see must be positive. After holding it, we can see whether the film is on the front or bottom of the film. On the reverse side, we can see that the black area on the side with the medicine film is non-reflective and matte, while the black area on the side without the medicine film has a shiny and reflective surface. If the drug film you see at this time is on the top, it is called upper film; if the drug film is on the reverse side, it is called underfilm.