| swk | StudyWorks! Teaching Pro: Mathematics Complete Save |
| swlt | SafeWallet Data |
| swm | Vim Swap Data |
| swml | SignWriting Markup Language Data |
| swn | Vim Swap Data |
| swo | Vim Swap Data |
| swp | General Swap File |
| swp | Vim Swap Data |
| swp | SolidWorks Macro |
| swq | SWAT Stream Water Quality Input Data |
| swr | SageWorld Anti-Hacker Program Output |
| swsd | Sodera Spectrum Data |
| swstd | SolidWorks Design Checker Data |
| swv | Sidewinder Game Voice Settings |
| swzk | SWiSH Wizard Data |
| sxcmp | SIMetrix Components Data |
| sxdat | SIMetrix Data |
| sxg | Stradx Segmentation Data |
| sxgph | SIMetrix Graph Binary Data |
| sxr | Stradx Registration Data |
| sxs | Str3Di Data |
| sxsch | SIMetrix Schematic Data |
| sxsnp | SIMetrix Snapshot Data |
| sxt | Formula Graphics Script |
| sxv | Action Repeater File |
| sxv4 | SuperSTAR Database |
| sxy | Spike2 XY Views Data |
| sy | Simplexety Data File |
| sy0 | WordExpress Data |
| sy1 | AMI Pro Smartpix Symbol Library |
| sy7 | Synchro Studio 7 Output Data |
| syc | Network Associates Sniffer Capture |
| syd | SYSTAT Data File |
| syg | SYSTAT Graph |
| syl | Symbolic Link Spreadsheet |