This format is used as the color palette format for a variety of operating system image editors. It is used to store font templates in text and graphic editors. It allows you to change color intensity and transparency levels.
was developed for the first mass-produced e-book reader – Rocket eBook. The format is written in Ruby. RB files are containers holding the entire content for a Rocket eBook device. It has DRM protection capability which is not used in the books published at present due to the format’s lack of popularity.