DDIF File

What are DDIF files and how to open them

Are you having problems opening a DDIF file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your DDIF files.

What is a DDIF file?

A .DDIF file is a DIGITAL Document Interchange Format file.

Digital Document Interchange Format is a format developed by Digital Equipment Corporation, designed for storing compound documents that combine text, graphics, images, and even audio in a revisable form. It serves as an interchange, storage, and application format within CDA (Compound Document Architecture) for documents that need to be edited or repurposed across different systems.

Documents in this format are created by CDA‐aware document processors, particularly under Digital's operating systems such as VMS or Ultrix. Once authored, they can be displayed, printed, stored, or exchanged across platforms. They support revision and extensibility, so that content can be altered or linked dynamically. The format is designed to enable display on both simple text‐only terminals and graphical, WYSIWYG workstations.

Internally, this format belongs to the DDIS/ASN.1 family of syntaxes and is formally known as the DDIF syntax under CDA. It is identified by the byte signature given in the evidence block: bytes "FF FF 7F 80 A0 80 80 10 01 81 01" at file offset zero.

How to open DDIF files

Important: Different programs may use files with the DDIF file extension for different purposes, so unless you are sure which format your DDIF file is, you may need to try a few different programs.

We have not yet verified any programs for Windows that work with this specific file format. If you know one, please use the 'Suggest a program' link below. Thanks!

Last updated: October 22, 2026

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