| dct | DeSmuME ROM Cheats Data |
| dct | E-Sword v8 Dictionary Data |
| dct5 | Microsoft Word 5 for Mac Dictionary Data |
| dctmp | DC++ Partially Downloaded |
| dctx | E-Sword v9 Dictionary Data |
| dctx | Microsoft Office IME Extended Dictionary Data |
| dctxc | Microsoft IME Dictionary Compiler File |
| dcv | DriveCrypt Volume |
| dcw | Draft Choice for Windows Drawing |
| dcy | NETSCAN Decay Search Results |
| dd | Everest Data Dictionary |
| dd | OMA Download Descriptor |
| dd | Sage MAS 90 DD Data |
| dd2 | OMA Download Agent v2 Descriptor |
| ddat | DivX Temporary Video Data |
| ddb | Act! Sales Data |
| ddb | Protel 99SE Design Database |
| ddb | TINA Shape Library Database |
| ddd | BullsEye Text Data |
| ddd | Digital Tachograph Data |
| ddd | Medlin Payroll Software Direct Deposit Data |
| ddd | Verity Server Data |
| dde | ABBYY Lingvo Dictionary Error Log |
| dde | Sage MAS 90 DDE Data |
| ddf | Bitstream Fontware Data |
| ddg | Deltadrive GRS Database |
| ddg | DucatiDiag Data File |
| ddg | MAP GMS Installation Document |
| ddi | MAP IEC Document |
| ddl | Ovation Pro DDL |
| ddoc | DigiDoc Digital Signature |
| ddp | Dinkey Dongle Parameter File |
| ddp | OS/2 Warp Device Driver Profile |
| ddr | DDRemote Saved Parameters |
| ddr | MAP Parameterisation Document |
