| CXI | Common X Interface |
| CAI | Common Air Interface |
| CPI | Common Programming Interface [IBM] |
| CAI | Common Air Interface [engl.] Definierte Schnittstelle für Funkanwendungen |
| CLI | Common Layer Interface |
| CCI | Common Client Interface |
| CSI | Common Synchronous Interface |
| CNI | Common Network Interface |
| CPI-C | Common Programming Interface for Communications [IBM] |
| CCI | Common Communications Interface [engl.] |
| CGI | Common Gateway Interface [engl.] Hostanbindung ans Web |
| CUI | Character/Common User Interface [IBM] |
| CAPI | Common ISDN Application Programming Interface |
| CAPI | Common Application Programming Interface [engl.] Telefonschnittstelle im PC |
| CAIS | Common APSE Interface Specification // Set [engl.] |
| CN | Common Name |
| BCE | Before the Common Era [substitute for BC] |
| COMHED | Common Header |
| MIC | Mode Indicate Common |
| CMB | Common Management Bus |
| OCC | Other Common Carrier |
| SCSA | Sun Common SCSI Architecture |
| SCC | Specialized Common Carrier |
| BCP | Best Common Practice [engl.] Bewährte Praxis |
| RCC | Radio Common Carrier |
| CSE | Common Subexpression Elimination |
| CORE | Common Runtime Environment |
| CPT | Common Point of Trust |
| CPL | Common Public License Open-Source-Lizenz |
| COMAL | Common Algorithmic Language |
| CAF | Common Assessment Framework Köln, http://www.caf-netzwerk.de |
| CLF | Common Logfile Format |
| CNRP | Common Name Resolution Protocol |
| COE | Common Operating Environment |
| CGS | Common Graphics System |
| CFM | Common Functional Model |
| CEM | Common Evaluation Methodology |
| CMC | Common Mail Call |
| CDL | Common Data Language |
| CCS | Common Channel Signalling |
| CCS | Common Command Set [engl.] |
| CPI | Common Part Indication |
| CCF | Common Cause Failure [engl.] Fehler mit gemeinsamer Ursache [in der Sicherheitsbetrachtung technischer Systeme] |
| CC | Common Criteria [engl.] Internationale Sicherheits-Prüfkriterien, Nachfolger von ITSEC |
| CIM | Common Information Model |
| CAL | Common Assembly Language |
| CIM | Common Information Model |
| CLR | Common Language Runtime |
| LCD | Lowest Common Denominator |
| CVE | Common Vulnerabilities and Exposures |