| gcod | G-code Code |
| gcode | G-code Code |
| gcp | Spectramap Group Properties |
| gcrd | GnomeCard vCard Data |
| gcs | Gamecube SharkSave Format Data |
| gcs | GameShark SharkSave Data |
| gct | GenePattern Gene Cluster Text |
| gctl | SCCM GIAM Control Data |
| gcw | Microsoft Mathematics Worksheet |
| gd | STK Database Update Information |
| gd1 | Gerber Drill Drawing Data |
| gd2 | Gerber Drill Drawing Data |
| gd3 | Gerber Drill Drawing Data |
| gd3 | GreatFamily Genealogy Data |
| gd3 | SNES ROM Image GD3 |
| gdb | Act! Group Database |
| gdb | Genbox Family History Database |
| gdb | GroupMail Database |
| gdb | TIGER Geodatabase |
| gdc | FME Desktop Grid Data Catalog |
| gdd | Gerber Drill Drawing Data |
| gde | GDE Data |
| gde | GlobalQSL Graphic Editor Data |
| gdf | 3DMove 3D Geological Model |
| gdf | FutuRUG Group Definition |
| gdf | GEOS Dictionary Data |
| gdf | GlossTeX Definition |
| gdf | SmartWare Pre 1.5 Graph Definitions Data |
| gdi | Sega Dreamcast GDI Image |
| gdiagramstyle | OmniGraffle Diagram Style |
