Storage format for images that can be used as graphic textures in 3D applications or computer games. It is also used in the CorelDRAW software as a Pantone Spot reference palette element for the purpose of applying colors to editable elements.
This format has the same color structure as RGB, but it includes an alpha channel that is used to display various levels of transparency. The transparency value is set from 0 to 1, where 1 corresponds to opacity. It is described using the CSS3 programming language.