| cdt | ImgBurn CD-Text Project |
| cedprj | Ashampoo CoverEditor Project |
| celtx | Celtx Project |
| cenon | Cenon Project |
| cenon~ | Cenon Project Backup |
| cep | CostOS Estimating Project |
| Vector NTI Assembly Project |
| cepx | Vector NTI Assembly Project |
| cer | Creatacard Certificate Project |
| cfp | C-Free Project |
| Subtitle Workshop Custom Format Project |
| cgp | Xilinx CORE Generator System Project |
| che | CHwinEHE Project |
| chkn | IMVU Project |
| chmprj | Abee CHM Maker Project |
| chp | CodeHealer Project |
| chproj | Adobe Character Animator Project |
| cin | Calculux Indoor Project |
| cinema4d | Maxon Cinema 4D Project |
| cl | CLwin Project |
| cl4 | Easy CD Creator 4 Project |
| cl5 | Roxio Easy CD Creator 5 Project |
| clg | Collage Maker Project |
| clk | Corel R.A.V.E Project |
| clpprj | CodeLobster IDE Project |
| clw | Grade Organizer Project |
| cmmcd | Camtasia Studio MenuMaker Project |
| cmmp | Camtasia MenuMaker Project |
| cmmtpl | Camtasia MenuMaker Template |
| cmproj | Camtasia for Mac Project |
| cms | Coach Project Archive |
| cna | Catena Project |
| cnp | Bentley CONNECT Project |
| companylogo | Company Logo Designer Project |
| con | Canoco Project |
| contentproj | XNA Game Studio Game Content Project |
| converterx | SiMX TextConverter Project |
| corelproject | Corel PhotoAlbum Project |
| cp | Adobe Captivate Project |
| cpb | Comicino Studio Project |
| cpdx | Adobe Captivate Storyboard Project |
| cpf | Cognos Framework Manager Project |
| cpg | Cool Page Project |
| cpj | WinOnCD Project |
| cpmz | Miradi ConPro Exported Project |
| cpr | ConTEXT Editor Project |
| cprj | CMSIS-Build Project |
| Cypress EZ-Click Project |
| cproj | Atmel Studio AVR GCC Project |
| cproject | Eclipse CDT Project |
| cptx | Adobe Captivate 5 Project |
| cpvc | Adobe Captivate Video Composition |
| cscproj | Colasoft Capsa Project |
| csdproj | Visual Studio .NET Visual C# Smart Device Project |
| csg | CounterSketch Design Project |
| csproj | Chaoscope Project |
| Visual Studio .NET Visual C# Project |
| ct7project | CrazyTalk Project |
| ctd | Sony ClickToDvd Project |
| ctk | TeKton3D Project |
| ctp | CrazyTalk Project |
| ctproject | Cartoon Animator Project |
| CrazyTalk Animator Project |
| ctv | Citavi Project |
| ctv3 | Citavi v3 Project |
| ctv6 | Citavi v6 Project |
| ctv6bak | Citavi v6 Project Backup |
| cwp | Cakewalk Sonar Project |
| cwprj | CanvasWorkspace Project |
| cwproj | COMPRESS Project |
| cwt | Cakewalk Sonar Template |
| cxl | ConsoXL Project |
| cxp | CX-Programmer Project |
| cxproj | Celena X Cell Analyzer Project |
| cyc | CYCAS CAD Project |
| cyg | Ashampoo Home Designer Project |
| cyp | Ashampoo Home Designer Pro Project |
| Home Designer Pro Project |
| d2h | Doc-To-Help Project |
| d2v | DGIndex Project |
