| sol | Adobe Flash Player Shared Object |
| sol | AMPL Solution File |
| songs | MediaShout Song Library |
| sor | Adobe Flash Media Server Client Side Shared Object |
| sor | OTDR Trace File |
| sos | Adventure SOS Compiled Walkthrough |
| sot | Adventure SOS Walkthrough Source |
| soundpack | SoundPackager Sound Package |
| sov | 3DCS Advanced Analyzer/Optimizer SOVA Model |
| sox | BiRT Spreadsheet Report Executable File |
| sp | STK Sensor Pointing File |
| sp | SignPlot Document |
| sp | Simplexety Parameter File |
| sp3 | NGS Standard Product 3 Format Data |
| spa | MikuMikuDance Sphere Mapping File |
| spc | Thermo Scientific SPC File |
| spc | Microsoft Software Publisher Certificate |
| spd | SpecTRM Specification |
| spd | Form Z Suspended Rendering FIle |
| spd | SPSD/M Database |
| spd | Windows Server Security Policy Database |
| spda | Surveyor PDA Detector Data |
| spdata | Microsoft SharePoint Project Data |
| spdb | iGO Primo SpeedCam Database |
| spe | SPSS Extension |
| spentry | Spartan Entry Database |
| spex | SPEX Data |
| spf | SQR Portable Format |
| spfs | Spider File Storage |
| spg | SG TCP Optimizer Backup |
| sph | Ribbons Sphere Definition |
| sph | MikuMikuDance Sphere Multiplied Map |
| spinput | Spartan Spinput Format File |
| spk | SPARKvue v1.0 Data |
| spk2 | SPARKvue v2.0 Data |
