| rwstyle | RapidWeaver Style File |
| rwtheme | RapidWeaver Theme File |
| rwx | RenderWare Script |
| rxd | RapidPLUS XML Application File |
| rxml | Roxen Macro Language Document |
| rxs | Borland Reflex Database Screen Driver Data |
| s | Assembly Source Code |
| s3e | Cocos2d-x S3E Executable |
| s43 | IAR System MSP430 Assembly Source Code |
| s4e | Airplay SDK Header File |
| s5d | STEP 5 Program |
| s5p | STEP 5 Project |
| s62 | Code::Blocks Assembly Source Code |
| s7f | STEP 7 Project |
| s7l | STEP 7 Library Data |
| s7p | STEP 7 Program |
| sa | Unix Shared Library |
| sac | Single Assignment C Code |
| sal | Gupta Scalable Application Language File |
| sap | Stadium Application |
| sapz | Stadium Archive |
| saq | SAS 6 Sequential Engine Access Descriptor Data |
| sas | SAS Program |
| sas7bpgm | SAS Stored Program |
| sas7bput | SAS Permanent Utility |
| sas7butl | SAS Utility |
| sass | Sass Indented Syntax Data |
| sb | Laird smartBASIC Source Code |
| sbr | Visual Studio Source Browser Data |
| sbsx | Microsoft Storyboard Shapes File |
