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 is used for storing several types of bitmaps, including animations. MNG allows you to store lossy and lossless images with compression. This format provides you with more options than GIF for saving animated files while keeping the original image size.