| as4a | ActivInspire Resource Pack |
| asas | ANSYS ASAS Input File |
| asat | TurboCAD Assemble SAT 3D Model |
| asb | Alphacam Stone VB Macro |
| asc | SOBEK RTC Communication Data |
| asc | Autodesk 3D Studio Scene in ASCII |
| asce | ASCE Data |
| asd | Ableton Warp Analysis File |
| ashlang | Ashampoo Media Player Language Data |
| asice | DigiDoc BDOC Digital Signature |
| asif | AEDT Standard Input Data |
| asj | Aldfaer Data File |
| ask | Ableton Live Skin |
| ask | AskSam Database |
| asl | Miranda IM Emotions Definition |
| aslquery | Mac OS X Console Query |
| asm | PTC Creo Assembly Data |
| asm | Alphacam Stone Param Macro |
| asmdot | SolidWorks Assembly Template |
| asmprp | SolidWorks Assembly Properties Template |
| asn | Abstract Syntax Notation One Data |
| asn | NCBI ASN.1 Data |
| asn1 | Abstract Syntax Notation One Data |
| asp | MGS Antenna SPK File |
| asp | Alphacam Stone Post Data |
| ass | FullProf Average Size Strain Plot Data |
| assetproj | Camtasia Studio Asset Information |
| assoc | Associate This File Association Database |
| asstore | Microsoft SQL Server Property String Store |
| assy | Siemens NX Assembly Data |
| ast | Adobe Color Separation Table |
| ast2 | Astrotite 200X Data |
| astm | Optitex 3D Suite ASTM Grading File |
| astore | LUX Variables Data |
| astore | Microsoft SQL Server Property Main Store |