This is a format for presenting fonts in PDF files that was initially conceived to store symbols in the Japanese and Chinese languages because it had a 16-bit structure and allowed for more precise adjustment. CID expands the the potential for PostScript by supporting languages that do not have a left-to-right orientation, and by supporting even a vertical mode of orientation.
This format was used to store bitmap and vector images natively on Macintosh computers. It was used for laying out and sharing images between programs. It used JPEG compression algorithms and RLE encoding. Today, the PICT format is used in the Windows environment with the PCT extension.