In OpenShift you may set aliases to servers. The client library does not support this yet.

--alias Specify server alias (when using add/remove-alias)

see here:
https://github.com/openshift/os-client-tools/blob/master/express/bin/rhc-ctl-app#L187
https://github.com/openshift/os-client-tools/blob/master/express/lib/rhc-common.rb#L593

Alias is used to have your OpenShift Express app showing up at your own domain name: https://www.redhat.com/openshift/forums/express/requests-for-features-enhancements#comment-9145