A common pattern is to extend an existing config, overriding and/or adding new config values to it. The extension is done by including the base configuration, and then overriding the chosen values in the current config.
This page assumes that you are familiar with the contents of The Defaults List.
To extend a config from a different config group, include it using an absolute path (/), and override the package to _here_. (_here_ is described in Packages)
It is otherwise identical to extending a config within the same config group.