X/Open was an independent international organization that started in 1984 and merged with the Open Software Foundation (OSF) in 1996 to form The Open Group (TOG).
During its years of existence, X/Open developed an open multivendor environment for Common Application Environment (CAE) based on the interface defined by the Institute of Electrical and Electronics Engineers (IEEE), which it later extended towards other open system requirements. Another model developed by X/Open is X/Open Distributed Transaction Processing (DTP). The X/Open developed guideline X/open Portability Guide (XPG) deals with standards to ensure compatibility between creator- and platform-independent systems.
The members of X/Open include companies from the information technology and telecommunications sectors.