DOC is a file extension for word processing documents. It is associated mainly with Microsoft Word application. DOC files can also contain charts and tables, videos, images, sounds and diagrams. It supports almost all the Operating Systems.

SIX is an alternative extension of the SIXEL bitmap graphics format. It was developed for terminals and printers by Digital Equipment Corporation (DEC). SIX actually means six pixels of which an image stored in the format consists. If you have a SIX file you want to view but you do not have an access to a DEC terminal, you need to convert it to a more popular format.