Multiple versions of an application or tool might be available in the same image. Each version of the application is available to users by specifying the full path. One version, called the preferred version, is available from a common directory such as /usr/bin for ease of use. If all versions participate in the same mediation, as described below, you can easily reset the version that is the preferred version. This administrative selection is retained across package updates.
A mediation is a set of links in which the link path is the same for each link in the set, and the target of each link is different. For example, the link path might be /usr/bin/myapp and targets of the link might include /usr/myapp/myapp1/bin/myapp and /usr/myapp/myapp2/bin/myapp. Each link in a mediation is called a participant in the mediation. If /usr/bin/myapp currently invokes myapp1, you can easily change the selection so that /usr/bin/myapp invokes myapp2. The version of the software that is currently the target of the link is the preferred version.