What is the CON file format?
A .con file is a WordPerfect Concordance file - a plain-text word list that drives the automatic index-generation feature in Corel WordPerfect. The file contains one word or phrase per line; WordPerfect scans the target document for each entry and builds an index with the matching page numbers automatically.
Concordance files eliminate the need to manually tag every occurrence of a term in a long document. An author prepares a .con file listing all terms to be indexed, attaches it during the index-generation step, and WordPerfect handles the rest. The feature has been part of WordPerfect since version 5.0 (1989) and remains available in current WordPerfect Office releases.
The format is intentionally simple - no header, no metadata, no markup. Entries are matched case-insensitively by default. The file is saved in Windows-1252 (ANSI) encoding for older WordPerfect versions, or UTF-8 in more recent releases.
A practical note: CON is a reserved device name in Windows (the system console / stdin-stdout). A file literally named con without a qualifying extension cannot be created at the Windows filesystem level. WordPerfect saves these files with the .con extension, which sidesteps the naming restriction. Attempting to create a bare con file from the command line will produce an error or hang in most Windows environments.
.con files can be created and edited in any plain-text editor, including Notepad. See also .wpd for the WordPerfect document files that reference concordance lists.
Security & safety
RISK: LOWPlain-text file; no execution risk. The .con device-name conflict (CON = Windows console) is a curiosity but poses no security risk for files named with the .con extension.
Format details
in a nutshell- Windows console device name - CON is a reserved DOS/Windows device name (keyboard input / screen output); not a file type but causes naming conflicts.
- Generic configuration file - Various applications use .con for configuration data (plain text or INI-style); no single dominant format.
- Connections/contact file (various apps) - Some database or CRM tools use .con for connection profile data; proprietary per-application.
Programs that open CON files
Windows2 apps
WordPerfect Office
Paid In WordPerfect, go to References → Define Index → select the .con file as the concordance. Edit it via File → Open as a text document. 
Technical details
deep spec| Developer | Corel Corporation (WordPerfect) |
| File type | Plain-text word list (no header or metadata) |
| Encoding | Windows-1252 (ANSI) for older WordPerfect versions; UTF-8 in recent releases |
| Structure | One word or phrase per line; no markup, no binary data |
| Purpose | Drives automatic document index generation in WordPerfect |
| Case sensitivity | Case-insensitive matching by default during index generation |
| Typical file size | 1 KB - 50 KB |
| Introduced | WordPerfect 5.0, 1989; feature carried through all subsequent versions |
| Operating system | Windows |
| Windows naming conflict | CON is a reserved Win32 device name; the .con extension bypasses the restriction |
| Companion format | .wpd WordPerfect Document that the concordance is applied to during index generation |
| Released | WordPerfect 5.x era (late 1980s - early 1990s) |
| Specification | support.corel.com |
CON conversions
Community Q&A
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