First customer ship. Historically it refers to a first release of a new Solaris (any Solaris) version. That version needed to pass all known regression tests an

First customer ship. Historically it refers to a first release of a new Solaris (any Solaris) version. That version needed to pass all known regression tests and needed to be suitable for use in mission critical production environments. Any time a commit to the code base would be made, it needed to satisfy that criteria, else Jeff Bonwick (the father of ZFS, who was the gatekeeper back then) would unceremoniously rip it out. Any kind of breakage, even during normal development, was unacceptable. This engineering ethos lives on in illumos and SmartOS, which is why commits to the code base are all about quality, not quantity. The commits might not be as frequent as elsewhere, but can pack tremendous amounts of functionality and must pass both peer reviews and all kinds of regression testing, not to mention have a complete and usable documentation, before being committed. In addition to all of this, as far as I am aware, no commits to the illumos code base may be made without a corresponding tracking identifier.