| Table Of Contents Format | |
| QUALCOMM | |
| Ads |
TOC file extension was used by no longer developed email client Eudora. TOC files stored email folder contents, including inbox, outbox, and trash subfolders.
Eudora was released in 1988 and since 1991, after being bought by Qualcomm, had been actively developed for next 15 years. Paid and free (with ads) versions were available. Since 2010 Eudora and TOC format development was droped definitely.
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| .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 |