What is the SDL file format?
An .sdl file is a Corel Paradox Delivered Script file - a compiled, distributable form of an ObjectPAL script written for the Paradox relational database application. The "delivered" designation means the source code has been compiled away: developers used the .sdl format to ship automation logic to end users without exposing the readable ObjectPAL source, which was stored in .sc script or .ssl form-script files.
ObjectPAL was the event-driven scripting language built into Paradox, used to automate database queries, form interactions, and report generation. When compiled to .sdl, the script became a proprietary binary file that the Paradox runtime could execute directly.
Paradox passed through several owners - Ansa Software, then Borland (1987), then Novell (1994), and finally Corel Corporation, which bundled it with WordPerfect Office. The last release was Paradox 11, included in Corel WordPerfect Office X3 (2006). Corel discontinued Paradox entirely after that version.
Because the .sdl format is proprietary and undocumented, no third-party tool is known to open or decompile these files. Legacy .sdl files from archived Paradox applications require a working Paradox 5-11 installation on Windows XP or earlier to run. Related source-level files include .sc (script source), .ssl (form script), and the Paradox table format .db.
Security & safety
RISK: LOWBinary script file for a discontinued database application. Cannot execute on modern systems without Paradox installed. No known malware vector.
Format details
in a nutshell- Simple Declarative Language (SDL) data file - SDL text files store structured data (lists, maps, trees) - entirely unrelated to Paradox scripts.
- SmartDraw Library file - SmartDraw uses .sdl for symbol/graphics library files.
- Alias|Wavefront Scene Description Language - 3D scene description format from Alias|Wavefront (now Autodesk Maya predecessor).
Programs that open SDL files
Windows2 apps
WordPerfect Office
Paid Current WordPerfect Office (X8+) no longer ships Paradox - cannot open SDL files. Use legacy WPO X3 version only. 
Corel Paradox (WordPerfect Office X3)
Paid Open Paradox, use File > Open Script or run from the IDE. Requires Windows XP/Vista era environment. Technical details
deep spec| Format type | Binary compiled ObjectPAL script (distributed/delivered form) |
| Encoding | Binary, little-endian (x86 Windows platform) |
| Scripting language | ObjectPAL - Paradox's event-driven scripting and database automation language |
| Purpose | Distribute automation logic without exposing ObjectPAL source code to end users |
| Source equivalents | `.sc` (script source) and `.ssl` (form-level script) contain the editable ObjectPAL source |
| Runtime engine | Paradox ObjectPAL execution engine (Paradox 5 through 11) |
| Supported platforms | Windows 95 / 98 / ME / 2000 / XP / Vista (Paradox 5-11) |
| Typical file size | Under 100 KB |
| Developer lineage | Ansa Software → Borland → Novell → Corel Corporation |
| End-of-life | Paradox 11 (Corel WordPerfect Office X3, 2006) was the last release; no current host application exists |
| Third-party support | No known decompiler or viewer; format is proprietary and undocumented |
| Released | ~1993 (Paradox for Windows era) |
| Latest version | Paradox 11 (shipped with Corel WordPerfect Office X3, 2006; final version) |
Community Q&A
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