| sok | Sokoban YASC Game Data |
| sol | Adobe Flash Player Shared Object |
| sol | PATCHMASTER Solution File |
| sol | AMPL Solution File |
| sol | SWAT Soil Input Data |
| sol | AquaCrop Soil Profile Data |
| solr | Apache SOLR Data |
| songs | MediaShout Song Library |
| sopcinfo | SOPC Builder Information |
| sor | OTDR Trace File |
| sor | Adobe Flash Media Server Client Side Shared Object |
| sos | Adventure SOS Compiled Walkthrough |
| sot | Hollowcore Manufacturing System SOT Data |
| sot | Adventure SOS Walkthrough Source |
| sot | CET Designer ProjectSymbols Standard Options Table |
| sou | WRAP Simulation Results Output Data |
| soundpack | SoundPackager Sound Package |
| sov | 3DCS Advanced Analyzer/Optimizer SOVA Model |
| sox | BiRT Spreadsheet Report Executable File |
| sp | Simplexety Parameter File |
| sp | SignPlot Document |
| sp | STK Sensor Pointing File |
| sp3 | NGS Standard Product 3 Format Data |
| spa | MikuMikuDance Sphere Mapping File |
| spa | Nicolet OMNIC Data |
| spbm | VMware vSphere Storage Policy Based Management Data |
| spc | Microsoft Software Publisher Certificate |
| spc | Galactic SPC Data |
| spc | Thermo Scientific SPC File |
| spc | Zemax Spectrum Source Data |