How to open .CPA files on iOS
To open .CPA files on iOS, iOS typically will not have a native viewer for chemical/x-compass; use the Files app to share the .CPA to a chemistry-capable app only if you already trust and use one, otherwise transfer the file to a desktop system for proper handling.
Step-by-step instructions
- iOS typically will not have a native viewer for chemical/x-compass; use the Files app to share the .CPA to a chemistry-capable app only if you already trust and use one, otherwise transfer the file to a desktop system for proper handling.
Common issues
The file opens in the wrong application (or no app is suggested)
Because .CPA is ambiguous and chemical/x-compass is not universally supported, your OS may not know what to do with it or may pick an unrelated app.
- Identify the producer of the file (original software/workflow) and open it there.
- On Linux, verify what MIME type is being assigned (often chemical/x-compass) and adjust file associations only if you have a known compatible application.
“Unsupported file format” or “file is corrupted” error
This often happens when the .CPA file is not actually a Compass Takahashi chemical file, or it was exported from a different product that also uses .CPA.
- Confirm with the sender what program created it and whether it can be re-exported to another, better-supported chemistry format.
- Try opening the file on a Linux system where shared-mime-info may classify it as chemical/x-compass to help narrow down the type.
MIME type confusion (chemical/x-compass not recognized)
chemical/x-compass appears in shared desktop MIME databases and chemistry extension lists, but it is not an IANA-registered media type, so some systems and tools may not recognize it.
- Treat the file as application-specific rather than relying on MIME type auto-detection.
- If you control the workflow, prefer exporting/sharing in a more widely recognized chemistry format for cross-platform use.
Security note
Treat .CPA files as untrusted input unless you know the source application: the extension is ambiguous, and opening unknown files in complex parsers can carry risk from malformed content.