This is a format for storing and presenting text information. It’s also referred to as CID 2 and is basically used for imaging and creating complex fonts in PDF. It’s based on the TrueType system, but allows for more precise adjustment and allows for refined writing due to a 16-bit structure that is very important when displaying Asian language symbols.
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.