| SketchUp Backup Format | |
| Trimble | |
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File with an .SKB extension contains a backup copy of a 3D object created in SketchUp software; it corresponds to an .SKP file. It is used in case of losing or damaging the original file, just change the extension from SKB into SKP.
Google SketchUp software is used for 3D modelling. It provides a functionality of automatic saving of project backup files in form of SKB files.
| .ab | Google Android Debug Bridge Backup Format |
| .aba | Palm Address Book Archive Format |
| .abbu | Apple Address Book Archive Format |
| .abf | Adobe Binary Screen Font Format |
| .abk | Ability Write Backup Format |
| .acp | Alfresco Exported Repository Format |
| .adi | Active@ Disk Image Format |
| .aea | Ae Timer Alarm Document Format |