Image comments are similar to environment variables. They have a name and optional value and are saved along with an image. They can be used to save human-readable information or data for use by other programs. RLE files store comments in a manner were they are retrievable. Comments may also be added to pixmaps. If a pixmap is then copied to an RLE file, the comments are also copied. PBM files add coments as text comments at the top of the file. However, they can be read by TSIPP once written.