| asv | Pegasus Mail Auto-saved Message |
| asv | QuarkXPress Autosave Data |
| asvx | MakeMusic Finale Auto-save File |
| aswcs | Avast Compressed Skin |
| asws | Avast Skin |
| asy | LTspice Symbols Data |
| asy | Xilinx CORE Generator Graphical Symbol File |
| at | ETCBC Analyzed Text Data |
| at1 | KJT-200 Absorbance Data |
| at4p | AmpliTube 4 Preset |
| at5p | AmpliTube 5 Preset |
| atb | Alphacam Lathe VB Macro |
| atb | AnetHelpTool Format Data |
| atc | AceText Collection File |
| atc | AttacheCase Encrypted File |
| atc | Autodesk AutoCAD Tool Catalog |
| atc_list | aTube Catcher Data |
| atd | Microsoft SMS Data |
| atf | ASAM Transfer Format XML Data |
| atf | Canvas Duotone Curve Data |
| atf | GenePix Axon Text File |
| atf | PCAnywhere Auto Transfer Data |
| atfx | ASAM Transfer Format XML Data |
| ath | Alienware AlienFX Theme |
| ath | Alphacam Lathe Thread |
| ath | Athena Task File |
| atheme | Amazing Clock Theme Data |
| atl | Artlantis 3D Scene |
| atl | AutoTap Log |
| atla | Artlantis v5 Archive |
