| ru | Java Russian Font Properties |
| ruby | Ruby Console Application |
| ruf | ProWorx NXT Address Used Tables Reference |
| rul | InstallShield Install Script |
| rules | Visual C++ Project Rules |
| ruleset | Visual Studio Code Analysis Rule Set |
| rvb | Rhino 3D Visual Basic Script |
| rvf | RichView Format Data |
| rvr | RapidPLUS Reviewer Application |
| rvt | VersaPro Reference View Table |
| rwplugin | RapidWeaver Plugin |
| rwsnippet | RapidWeaver Snippet File |
| rwstyle | RapidWeaver Style File |
| rwtheme | RapidWeaver Theme File |
| rxd | RapidPLUS XML Application File |
| s | Assembly Source Code |
| s5d | STEP 5 Program |
| s5p | STEP 5 Project |
| s7f | STEP 7 Project |
| 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 |
| sas | SAS Program |
| sas7bpgm | SAS Stored Program |
| sas7bput | SAS Permanent Utility |
| sas7butl | SAS Utility |
| sass | Syntactically Awesome Stylesheets |
