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What is a .cd4 file?
A .cd4 file is a Discus Project File (version 4). This one is a specialist format without an obvious everyday home.
How to open a .cd4 file
- The program that created it is by far the most reliable way to open it.
- On Windows, use a hex viewer or the free TrID tool to identify what the file really is.
- On Mac or Linux, running `file yourfile` in the terminal identifies most formats instantly.
The registry records this extension against Discus Project File, so software from that family is the most likely match.
How to convert a .cd4 file
- Identify the file first, then look for an export or Save As option in whatever program can read it.
The technical record
For archivists, developers and the merely curious: these are the PRONOM registry entries for .cd4.
| Format name | Version | MIME type | PUID |
|---|---|---|---|
| Discus Project File | 4 | — | fmt/2104 |