Operating system development then split into two camps. The CDC-sanctioned evolution of COS was undertaken at the Sunnyvale, California software development laboratory. Many customers eventually took delivery of their systems with this software, then known as SCOPE (Supervisory Control Of Program Execution). SCOPE version 1 was, essentially, dis-assembled COS; SCOPE version 2 included new device and file system support; SCOPE version 3 included permanent file support, EI/200 remote batch support, and INTERCOM time-sharing support. SCOPE always had significant reliability and maintainability issues.