| sdff | IBM SDK for Java System Dump |
| sdm | System Definition Model |
| sdq | SAS Data |
| sdt | IBM Rational SDL Suite Data |
| se | Shuttle Source |
| seam | Seam Framework Java Servlet |
| seestyle | Coda Style Sheet |
| sem | Alpha Five Set Object |
| servoy | Servoy Archive |
| set | Alpha Five Set Data Dictionary |
| sex | Alpha Five Set Index |
| sexi | Alpha Five Set Index |
| sfsm | SPLat Tabula File |
| sgpbpr | SGP Baltie Program |
| sgpsc | SGP Baltie Scene |
| sh | Unix Shell Script |
| sho | Alpha Four Sort List |
| sil | SmartInspect Log |
| sip | SIP Specification File |
| 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 |
| skincfg | DevExpress VCL Skin Configuration |
| skv | Microsoft BizTalk Server XLANG Schedule Drawing |
| skx | Microsoft BizTalk Server XLANG Schedule |
| sl4 | GEMPACK Solution File |
| slax | Juniper SLAX Script |
| slim | RenderMan Slim Script |
| sll | PowerBASIC Static Link Library |
| slm | Microsoft Source Library Management File |
| sln | Microsoft Visual Studio Solution |
| slp | Adobe RoboHelp Screen Layout Page |
| slz | Adobe RoboHelp Exported Screen Layout |