| cmw | Custom Maintenance Wizard Data |
| cmxl | Microsoft Pivot Collection Data |
| cmy | CorelDRAW Custom CMY Data |
| cmz | Poser Compressed Camera Data |
| cn | GenePattern Copy Number Data |
| cn | RMCProfile Nitrogen Carbon Neighbours Data |
| cnb | Pegasus Mail Noticeboard Message |
| cnc | QuickCAM Pro CNC Machine Tool Path |
| cndf | Compressed NDF File |
| cne | Ancora Conserved Noncoding Elements Data |
| cng | CryptoNG Encrypted File |
| cni | CWBench Data |
| cnivg | CadnaR Voxel Grid Data |
| cnj | Acharya Conjunct Data |
| cnm | Pegasus Mail New Message |
| cnn | CNVkit Data |
| cno | TSP-INet Server Error Description Data |
| cnr | CRiSP Harvest Chinook Non-retention Data |
| cnt | ENVI PPI Count Data |
| cnt | IBM Rational Rose Contents Tab |
| cnu | iiV Lookup Script |
| cnv | PLINK Segmental Copy Number Variant Data |
| cnv | Tekla Structures Conversion File |
| cnw | DSC Crossover Network Tuning Data |
| cnx | IBM Rational XDE Component Instance File |
| cnx | Trimble LM80 Data |
| co2 | AquaCrop Atmospheric CO2 Data |
| coa | Medlin Payroll Software Chart Data |
| cod | SWAT Input Control Data |
| cod | WindLDR Binary PLC Data |
| codec | Rockbox Codec |
| coe | Xilinx CORE Generator Coefficients |
| cof | LightCycler v4 Coefficient Data |
| cog | SolidWorks Enterprise PDM Copied Log |
| cojt | Tecnomatix Kinematics Data |
