| sexi | Alpha Five Set Index |
| sfd | µVision Intermediary Pseudo-XML Data |
| sfla | MATLAB Shuffled Frog-Leaping Algorithm Data |
| sflb | Sitefinity Library |
| sfr | IAR System Special Function Register Definitions Data |
| sfr | µVision System Viewer Binary Data |
| sfsm | SPLat Tabula File |
| sgd | VT Pro-e Smart Graphics Definitions Data |
| sgpbpr | SGP Baltie Program |
| sgpsc | SGP Baltie Scene |
| sh | Unix Shell Script |
| sho | Alpha Four Sort List |
| sig | Uniface Component Signature Data |
| sil | SmartInspect Log |
| simple | Simple Source Code |
| sip | SIP Specification File |
| siq | SAS 6 Sequential Engine Index Data |
| sitemap | ASP.NET Site Map |
| sja | SourceJammer Data |
| sjava | Synchronous Java Source Code |
| sjc | Sothink JavaScript Web Scroller Definition Data |
| skein | Inform 7 Skein XML File |
| skin | Amazon Lumberyard Skinned Character Data |
| skincfg | DevExpress VCL Skin Configuration |
| skv | Microsoft BizTalk Server XLANG Schedule Drawing |
| skx | Microsoft BizTalk Server XLANG Schedule |
| sl | DataFlex Selection List |
| sl4 | GEMPACK Solution File |
| slax | Juniper SLAX Script |
| slim | RenderMan Slim Script |