Every CloudBees Jenkins solution is based on a custom build of the Jenkins core. These CloudBees core releases are based on the Jenkins community's Long-Term Support (LTS) releases. This page compiles the release notes of Jenkins Core versions included in the different products:
z < 10means that a community-built Jenkins LTS core has been used.
z < 10means that a CloudBees-built Jenkins LTS core has been used, which should contain the same content that the
z > 10represents CloudBees-built Jenkins LTS cores that include additional backports, such as security fixes released after community support for the that LTS line has ended.
The documentation is available here.