The file names of image sequences generally end in a number before the extension, for example image0001.rgb, image0002.rgb, image0003.rgb, and so on. When browsing for files like this, you may notice that the sequence appears as image####.rgb. Here, #### is Nuke’s way of indicating that the number is in a 4-digit incremental format. For a 3-digit format, such as image001.rgb, the frame number variable would be ###.
Nuke’s File Browser also understands unpadded file names, such as image1.rgb, image2.rgb, image3.rgb, and so on. They appear as image#.rgb.