| Delphi MultiHelp Index Format | |
| Autodesk | |
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HDX is a file format used by Delphi Intergrated Development Environment (IDE), a software developement package for developing console, web, and mobile games.
HDX stores index of Delphi help system topics. HDX files are created by combining KWF files using HelpInst.exe program. KWF (keyword files) are generated by kwgen.exe tool.
Windows
| .aawdef | Ad-Aware Definitions Format |
| .abr | Adobe Photoshop Brush Format |
| .ac$ | AutoCAD Undo Info Format |
| .acc | DR DOS - ViewMax Format |
| .acl | Microsoft Office Automatic Correction List |
| .acs | Microsoft Agent Character Structured Storage Format |
| .ad | After Dark Screen Saver Format |
| .add | Microsoft Dynamics AX Developer Documentation Format |