| rst | reStructuredText File |
| rtab | Randy Tab Guitar Tablature |
| rtb | CA Report Template Builder Document |
| rtd | RagTime Document |
| rtdf | Rich Text Format Document |
| rtf | Rich Text Format Document |
| rtfd | Rich Text Format Document |
| rtfd | TextEdit Document |
| rtg | Autodesk Maya 3D Scene Data |
| rtml | Runeberg Text Markup Language Document |
| rtt | RagTime Form |
| rtx | Rich Text Format Document |
| rvt | Autodesk Revit Document |
| rxl | Seetrax XL Designer Document |
| s1a | Sealed PDF Document |
| s1e | Sealed Excel Worksheet |
| s1w | Sealed Word Document |
| s3d | Shape 3D v8 Document |
| s3dx | Shape 3D X Document |
| s3g | MakerBot S3G Document |
| s7 | Sibelius Music Notation |
| sadl | Semantic Application Design Language Document |
| sam | Ami Pro Document |
| sb1 | MemoryMixer Album |
| sbk | Scrapbook Factory Deluxe Scrapbook |
| sbml | Systems Biology Markup Language Document |
| sbp | Autodesk Sketchbook Express Image |
| sbpf | Small Business Publisher Document |
| sbsc | Adobe Soundbooth Score Document |
| sbst | Adobe Soundbooth Score Template |
| sc2 | Microsoft Schedule Plus Interchange |
| scd | Microsoft Schedule Plus Document |
| scdoc | SpaceClaim Document |
| sch | EAGLE Schematic File |
| sch | KiCad Schematic Document |